Environmental Dermatology

The genus Leishmania comprises protozoan parasites that cause approximately 2 million new cases of leishmaniasis each year across 98 countries.¹ These protozoa are obligate intracellular parasites of phlebotomine sandfly species that transmit leishmaniasis and result in a considerable parasitic cause of fatalities globally, second only to malaria.^2,3

Phlebotomine sandflies primarily live in tropical and subtropical regions and function as vectors for many pathogens in addition to Leishmania species, such as Bartonella species and arboviruses.³ In 2004, it was noted that the majority of leishmaniasis cases affected developing countries: 90% of visceral leishmaniasis cases occurred in Bangladesh, India, Nepal, Sudan, and Brazil, and 90% of cutaneous leishmaniasis cases occurred in Afghanistan, Algeria, Brazil, Iran, Peru, Saudi Arabia, and Syria.⁴ Of note, with recent environmental changes, phlebotomine sandflies have gradually migrated to more northerly latitudes, extending into Europe.⁵

Twenty Leishmania species and 30 sandfly species have been identified as causes of leishmaniasis.⁴Leishmania infection occurs when an infected sandfly bites a mammalian host and transmits the parasite’s flagellated form, known as a promastigote. Host inflammatory cells, such as monocytes and dendritic cells, phagocytize parasites that enter the skin. The interaction between parasites and dendritic cells become an important factor in the outcome of Leishmania infection in the host because dendritic cells promote development of CD4 and CD8 T lymphocytes with specificity to target Leishmania parasites and protect the host.¹

The number of cases of leishmaniasis has increased worldwide, most likely due to changes in the environment and human behaviors such as urbanization, the creation of new settlements, and migration from rural to urban areas.^3,5 Important risk factors in individual patients include malnutrition; low-quality housing and sanitation; a history of migration or travel; and immunosuppression, such as that caused by HIV co-infection.^2,5

Case Report

An otherwise healthy 25-year-old Bangladeshi man presented to our community hospital for evaluation of a painful leg ulcer of 1 month’s duration. The patient had migrated from Bangladesh to Panama, then to Costa Rica, followed by Guatemala, Honduras, Mexico, and, last, Texas. In Texas, he was identified by the US Immigration and Customs Enforcement, transported to a detention facility, and transferred to this hospital shortly afterward.

The patient reported that, during his extensive migration, he had lived in the jungle and reported what he described as mosquito bites on the legs. He subsequently developed a 3-cm ulcerated and crusted plaque with rolled borders on the right medial ankle (Figure 1). In addition, he had a palpable nodular cord on the medial leg from the ankle lesion to the mid thigh that was consistent with lymphocutaneous spread. Ultrasonography was negative for deep-vein thrombosis.

CT112004016_e_Fig1_AB.jpg

Because the patient’s recent migration from Central America was highly concerning for microbial infection, vancomycin and piperacillin-tazobactam were started empirically on admission. A punch biopsy from the right medial ankle was nondiagnostic, showing acute and chronic necrotizing inflammation along with numerous epithelioid histiocytes with a vaguely granulomatous appearance (Figure 2). A specimen from the right medial ankle that had already been taken by an astute border patrol medical provider was sent to the Centers for Disease Control and Prevention (CDC) for polymerase chain reaction analysis following admission and was found to be positive for Leishmania panamensis.

CT112004016_e_Fig2_AB.jpg

Given the concern for mucocutaneous leishmaniasis with this particular species, otolaryngology was consulted; however, the patient did not demonstrate mucocutaneous disease. Because of the elevated risk for persistent disease with L panamensis, systemic therapy was indicated and administered: IV amphotericin B 200 mg on days 1 through 5 and again on day 10. Improvement in the ulcer was seen after the 10-day regimen was completed.

Comment

Leishmaniasis can be broadly classified by geographic region or clinical presentation. Under the geographic region system, leishmaniasis can be categorized as Old World or New World. Old World leishmaniasis primarily is transmitted by Phlebotomus sandflies and carries the parasites Leishmania major and Leishmania tropica, among others. New World leishmaniasis is caused by Lutzomyia sandflies, which carry Leishmania mexicana, Leishmania braziliensis, Leishmania amazonensis, and others.⁶

Our patient presented with cutaneous leishmaniasis, one of 4 primary clinical disease forms of leishmaniasis; the other 3 forms under this classification system are diffuse cutaneous, mucocutaneous, and visceral leishmaniasis, also known as kala-azar.^3,6 Cutaneous leishmaniasis is limited to the skin, particularly the face and extremities. This form is more common with Old World vectors, with most cases occurring in Peru, Brazil, and the Middle East. In Old World cutaneous leishmaniasis, the disease begins with a solitary nodule at the site of the bite that ulcerates and can continue to spread in a sporotrichoid pattern. This cutaneous form tends to heal slowly over months to years with residual scarring. New World cutaneous leishmaniasis can present with a variety of clinical manifestations, including ulcerative, sarcoidlike, miliary, and nodular lesions.^6,7

The diffuse form of cutaneous leishmaniasis begins in a similar manner to the Old World cutaneous form: a single nodule spreads widely over the body, especially the nose, and covers the patient’s skin with keloidal or verrucous lesions that do not ulcerate. These nodules contain large groupings of Leishmania-filled foamy macrophages. Often, patients with diffuse cutaneous leishmaniasis are immunosuppressed and are unable to develop an immune response to leishmanin and other skin antigens.^6,7

Mucocutaneous leishmaniasis predominantly is caused by the New World species L braziliensis but also has been attributed to L amazonensis, L panamensis, and L guyanensis. This form manifests as mucosal lesions that can develop simultaneously with cutaneous lesions but more commonly appear months to years after resolution of the skin infection. Patients often present with ulceration of the lip, nose, and oropharynx, and destruction of the nasopharynx can result in severe consequences such as obstruction of the airway and perforation of the nasal septum (also known as espundia).^6,7

The most severe presentation of leishmaniasis is the visceral form (kala-azar), which presents with parasitic infection of the liver, spleen, and bone marrow. Most commonly caused by Leishmania donovani, Leishmania infantum, and Leishmania chagasi, this form has a long incubation period spanning months to years before presenting with diarrhea, hepatomegaly, splenomegaly, darkening of the skin (in Hindi, kala-azar means “black fever”), pancytopenia, lymphadenopathy, nephritis, and intestinal hemorrhage, among other severe manifestations. Visceral leishmaniasis has a poor prognosis: patients succumb to disease within 2 years if not treated.^6,7

Diagnosis—Diagnosing leishmaniasis starts with a complete personal and medical history, paying close attention to travel and exposures. Diagnosis is most successfully performed by polymerase chain reaction analysis, which is both highly sensitive and specific but also can be determined by culture using Novy-McNeal-Nicolle medium or by light microscopy. Histologic findings include the marquee sign, which describes an array of amastigotes (promastigotes that have developed into the intracellular tissue-stage form) with kinetoplasts surrounding the periphery of parasitized histiocytes. Giemsa staining can be helpful in identifying organisms.^2,6,7

The diagnosis in our case was challenging, as none of the above findings were seen in our patient. The specimen taken by the border patrol medical provider was negative on Gram, Giemsa, and Grocott-Gömöri methenamine silver staining; no amastigotes were identified. Another diagnostic modality (not performed in our patient) is the Montenegro delayed skin-reaction test, which often is positive in patients with cutaneous leishmaniasis but also yields a positive result in patients who have been cured of Leishmania infection.⁶

An important consideration in the diagnostic workup of leishmaniasis is that collaboration with the CDC can be helpful, such as in our case, as they provide clear guidance for specimen collection and processing.²

Treatment—Treating leishmaniasis is challenging and complex. Even the initial decision to treat depends on several factors, including the form of infection. Most visceral and mucocutaneous infections should be treated due to both the lack of self-resolution of these forms and the higher risk for a potentially life-threatening disease course; in contrast, cutaneous forms require further consideration before initiating treatment. Some indicators for treating cutaneous leishmaniasis include widespread infection, intention to decrease scarring, and lesions with the potential to cause further complications (eg, on the face or ears or close to joints).^6-8

The treatment of choice for cutaneous and mucocutaneous leishmaniasis is pentavalent antimony; however, this drug can only be obtained in the United States for investigational use, requiring approval by the CDC. A 20-day intravenous or intramuscular course of 20 mg/kg per day typically is used for cutaneous cases; a 28-day course typically is used for mucosal forms.

Amphotericin B is not only the treatment of choice for visceral leishmaniasis but also is an important alternative therapy for patients with mucosal leishmaniasis or who are co-infected with HIV. Patients with visceral infection also should receive supportive care for any concomitant afflictions, such as malnutrition or other infections. Although different regimens have been described, the US Food and Drug Administration has created outlines of specific intravenous infusion schedules for liposomal amphotericin B in immunocompetent and immunosuppressed patients.⁸ Liposomal amphotericin B also has a more favorable toxicity profile than conventional amphotericin B deoxycholate, which is otherwise effective in combating visceral leishmaniasis.^6-8

Other treatments that have been attempted include pentamidine, miltefosine, thermotherapy, oral itraconazole and fluconazole, rifampicin, metronidazole and cotrimoxazole, dapsone, photodynamic therapy, thermotherapy, topical paromomycin formulations, intralesional pentavalent antimony, and laser cryotherapy. Notable among these other agents is miltefosine, a US Food and Drug Administration–approved oral medication for adults and adolescents (used off-label for patients younger than 12 years) with cutaneous leishmaniasis caused by L braziliensis, L panamensis, or L guyanensis. Other oral options mentioned include the so-called azole antifungal medications, which historically have produced variable results. From the CDC’s reports, ketoconazole was moderately effective in Guatemala and Panama,⁸ whereas itraconazole did not demonstrate efficacy in Colombia, and the efficacy of fluconazole was inconsistent in different countries.⁸ When considering one of the local (as opposed to oral and parenteral) therapies mentioned, the extent of cutaneous findings as well as the risk of mucosal spread should be factored in.^6-8

Understandably, a number of considerations can come into play in determining the appropriate treatment modality, including body region affected, clinical form, severity, and Leishmania species.^6-8 Our case is of particular interest because it demonstrates the complexities behind the diagnosis and treatment of cutaneous leishmaniasis, with careful consideration geared toward the species; for example, because our patient was infected with L panamensis, which is known to cause mucocutaneous disease, the infectious disease service decided to pursue systemic therapy with amphotericin B rather than topical treatment.

Prevention—Vector control is the primary means of preventing leishmaniasis under 2 umbrellas: environmental management and synthetic insecticides. The goal of environmental management is to eliminate the phlebotomine sandfly habitat; this was the primary method of vector control until 1940. Until that time, tree stumps were removed, indoor cracks and crevices were filled to prevent sandfly emergence, and areas around animal shelters were cleaned. These methods were highly dependent on community awareness and involvement; today, they can be combined with synthetic insecticides to offer maximum protection.

Synthetic insecticides include indoor sprays, treated nets, repellents, and impregnated dog collars, all of which control sandflies. However, the use of these insecticides in endemic areas, such as India, has driven development of insecticide resistance in many sandfly vector species.³

As of 2020, 5 vaccines against Leishmania have been created. Two are approved–one in Brazil and one in Uzbekistan–for human use as immunotherapy, while the other 3 have been developed to immunize dogs in Brazil. However, the effectiveness of these vaccines is under debate. First, one of the vaccines used as immunotherapy for cutaneous leishmaniasis must be used in combination with conventional chemotherapy; second, long-term effects of the canine vaccine are unknown.¹ A preventive vaccine for humans is under development.^1,3

Final Thoughts

Leishmaniasis remains a notable parasitic disease that is increasing in prevalence worldwide. Clinicians should be aware of this disease because early detection and treatment are essential to control infection.³ Health care providers in the United States should be especially aware of this condition among patients who have a history of travel or migration; those in Texas should recognize the current endemic status of leishmaniasis there.^4,6

The genus Leishmania comprises protozoan parasites that cause approximately 2 million new cases of leishmaniasis each year across 98 countries.¹ These protozoa are obligate intracellular parasites of phlebotomine sandfly species that transmit leishmaniasis and result in a considerable parasitic cause of fatalities globally, second only to malaria.^2,3

Phlebotomine sandflies primarily live in tropical and subtropical regions and function as vectors for many pathogens in addition to Leishmania species, such as Bartonella species and arboviruses.³ In 2004, it was noted that the majority of leishmaniasis cases affected developing countries: 90% of visceral leishmaniasis cases occurred in Bangladesh, India, Nepal, Sudan, and Brazil, and 90% of cutaneous leishmaniasis cases occurred in Afghanistan, Algeria, Brazil, Iran, Peru, Saudi Arabia, and Syria.⁴ Of note, with recent environmental changes, phlebotomine sandflies have gradually migrated to more northerly latitudes, extending into Europe.⁵

Twenty Leishmania species and 30 sandfly species have been identified as causes of leishmaniasis.⁴Leishmania infection occurs when an infected sandfly bites a mammalian host and transmits the parasite’s flagellated form, known as a promastigote. Host inflammatory cells, such as monocytes and dendritic cells, phagocytize parasites that enter the skin. The interaction between parasites and dendritic cells become an important factor in the outcome of Leishmania infection in the host because dendritic cells promote development of CD4 and CD8 T lymphocytes with specificity to target Leishmania parasites and protect the host.¹

The number of cases of leishmaniasis has increased worldwide, most likely due to changes in the environment and human behaviors such as urbanization, the creation of new settlements, and migration from rural to urban areas.^3,5 Important risk factors in individual patients include malnutrition; low-quality housing and sanitation; a history of migration or travel; and immunosuppression, such as that caused by HIV co-infection.^2,5

Case Report

An otherwise healthy 25-year-old Bangladeshi man presented to our community hospital for evaluation of a painful leg ulcer of 1 month’s duration. The patient had migrated from Bangladesh to Panama, then to Costa Rica, followed by Guatemala, Honduras, Mexico, and, last, Texas. In Texas, he was identified by the US Immigration and Customs Enforcement, transported to a detention facility, and transferred to this hospital shortly afterward.

The patient reported that, during his extensive migration, he had lived in the jungle and reported what he described as mosquito bites on the legs. He subsequently developed a 3-cm ulcerated and crusted plaque with rolled borders on the right medial ankle (Figure 1). In addition, he had a palpable nodular cord on the medial leg from the ankle lesion to the mid thigh that was consistent with lymphocutaneous spread. Ultrasonography was negative for deep-vein thrombosis.

CT112004016_e_Fig1_AB.jpg

Because the patient’s recent migration from Central America was highly concerning for microbial infection, vancomycin and piperacillin-tazobactam were started empirically on admission. A punch biopsy from the right medial ankle was nondiagnostic, showing acute and chronic necrotizing inflammation along with numerous epithelioid histiocytes with a vaguely granulomatous appearance (Figure 2). A specimen from the right medial ankle that had already been taken by an astute border patrol medical provider was sent to the Centers for Disease Control and Prevention (CDC) for polymerase chain reaction analysis following admission and was found to be positive for Leishmania panamensis.

CT112004016_e_Fig2_AB.jpg

Given the concern for mucocutaneous leishmaniasis with this particular species, otolaryngology was consulted; however, the patient did not demonstrate mucocutaneous disease. Because of the elevated risk for persistent disease with L panamensis, systemic therapy was indicated and administered: IV amphotericin B 200 mg on days 1 through 5 and again on day 10. Improvement in the ulcer was seen after the 10-day regimen was completed.

Comment

Leishmaniasis can be broadly classified by geographic region or clinical presentation. Under the geographic region system, leishmaniasis can be categorized as Old World or New World. Old World leishmaniasis primarily is transmitted by Phlebotomus sandflies and carries the parasites Leishmania major and Leishmania tropica, among others. New World leishmaniasis is caused by Lutzomyia sandflies, which carry Leishmania mexicana, Leishmania braziliensis, Leishmania amazonensis, and others.⁶

Our patient presented with cutaneous leishmaniasis, one of 4 primary clinical disease forms of leishmaniasis; the other 3 forms under this classification system are diffuse cutaneous, mucocutaneous, and visceral leishmaniasis, also known as kala-azar.^3,6 Cutaneous leishmaniasis is limited to the skin, particularly the face and extremities. This form is more common with Old World vectors, with most cases occurring in Peru, Brazil, and the Middle East. In Old World cutaneous leishmaniasis, the disease begins with a solitary nodule at the site of the bite that ulcerates and can continue to spread in a sporotrichoid pattern. This cutaneous form tends to heal slowly over months to years with residual scarring. New World cutaneous leishmaniasis can present with a variety of clinical manifestations, including ulcerative, sarcoidlike, miliary, and nodular lesions.^6,7

The diffuse form of cutaneous leishmaniasis begins in a similar manner to the Old World cutaneous form: a single nodule spreads widely over the body, especially the nose, and covers the patient’s skin with keloidal or verrucous lesions that do not ulcerate. These nodules contain large groupings of Leishmania-filled foamy macrophages. Often, patients with diffuse cutaneous leishmaniasis are immunosuppressed and are unable to develop an immune response to leishmanin and other skin antigens.^6,7

Mucocutaneous leishmaniasis predominantly is caused by the New World species L braziliensis but also has been attributed to L amazonensis, L panamensis, and L guyanensis. This form manifests as mucosal lesions that can develop simultaneously with cutaneous lesions but more commonly appear months to years after resolution of the skin infection. Patients often present with ulceration of the lip, nose, and oropharynx, and destruction of the nasopharynx can result in severe consequences such as obstruction of the airway and perforation of the nasal septum (also known as espundia).^6,7

The most severe presentation of leishmaniasis is the visceral form (kala-azar), which presents with parasitic infection of the liver, spleen, and bone marrow. Most commonly caused by Leishmania donovani, Leishmania infantum, and Leishmania chagasi, this form has a long incubation period spanning months to years before presenting with diarrhea, hepatomegaly, splenomegaly, darkening of the skin (in Hindi, kala-azar means “black fever”), pancytopenia, lymphadenopathy, nephritis, and intestinal hemorrhage, among other severe manifestations. Visceral leishmaniasis has a poor prognosis: patients succumb to disease within 2 years if not treated.^6,7

Diagnosis—Diagnosing leishmaniasis starts with a complete personal and medical history, paying close attention to travel and exposures. Diagnosis is most successfully performed by polymerase chain reaction analysis, which is both highly sensitive and specific but also can be determined by culture using Novy-McNeal-Nicolle medium or by light microscopy. Histologic findings include the marquee sign, which describes an array of amastigotes (promastigotes that have developed into the intracellular tissue-stage form) with kinetoplasts surrounding the periphery of parasitized histiocytes. Giemsa staining can be helpful in identifying organisms.^2,6,7

The diagnosis in our case was challenging, as none of the above findings were seen in our patient. The specimen taken by the border patrol medical provider was negative on Gram, Giemsa, and Grocott-Gömöri methenamine silver staining; no amastigotes were identified. Another diagnostic modality (not performed in our patient) is the Montenegro delayed skin-reaction test, which often is positive in patients with cutaneous leishmaniasis but also yields a positive result in patients who have been cured of Leishmania infection.⁶

An important consideration in the diagnostic workup of leishmaniasis is that collaboration with the CDC can be helpful, such as in our case, as they provide clear guidance for specimen collection and processing.²

Treatment—Treating leishmaniasis is challenging and complex. Even the initial decision to treat depends on several factors, including the form of infection. Most visceral and mucocutaneous infections should be treated due to both the lack of self-resolution of these forms and the higher risk for a potentially life-threatening disease course; in contrast, cutaneous forms require further consideration before initiating treatment. Some indicators for treating cutaneous leishmaniasis include widespread infection, intention to decrease scarring, and lesions with the potential to cause further complications (eg, on the face or ears or close to joints).^6-8

The treatment of choice for cutaneous and mucocutaneous leishmaniasis is pentavalent antimony; however, this drug can only be obtained in the United States for investigational use, requiring approval by the CDC. A 20-day intravenous or intramuscular course of 20 mg/kg per day typically is used for cutaneous cases; a 28-day course typically is used for mucosal forms.

Amphotericin B is not only the treatment of choice for visceral leishmaniasis but also is an important alternative therapy for patients with mucosal leishmaniasis or who are co-infected with HIV. Patients with visceral infection also should receive supportive care for any concomitant afflictions, such as malnutrition or other infections. Although different regimens have been described, the US Food and Drug Administration has created outlines of specific intravenous infusion schedules for liposomal amphotericin B in immunocompetent and immunosuppressed patients.⁸ Liposomal amphotericin B also has a more favorable toxicity profile than conventional amphotericin B deoxycholate, which is otherwise effective in combating visceral leishmaniasis.^6-8

Other treatments that have been attempted include pentamidine, miltefosine, thermotherapy, oral itraconazole and fluconazole, rifampicin, metronidazole and cotrimoxazole, dapsone, photodynamic therapy, thermotherapy, topical paromomycin formulations, intralesional pentavalent antimony, and laser cryotherapy. Notable among these other agents is miltefosine, a US Food and Drug Administration–approved oral medication for adults and adolescents (used off-label for patients younger than 12 years) with cutaneous leishmaniasis caused by L braziliensis, L panamensis, or L guyanensis. Other oral options mentioned include the so-called azole antifungal medications, which historically have produced variable results. From the CDC’s reports, ketoconazole was moderately effective in Guatemala and Panama,⁸ whereas itraconazole did not demonstrate efficacy in Colombia, and the efficacy of fluconazole was inconsistent in different countries.⁸ When considering one of the local (as opposed to oral and parenteral) therapies mentioned, the extent of cutaneous findings as well as the risk of mucosal spread should be factored in.^6-8

Understandably, a number of considerations can come into play in determining the appropriate treatment modality, including body region affected, clinical form, severity, and Leishmania species.^6-8 Our case is of particular interest because it demonstrates the complexities behind the diagnosis and treatment of cutaneous leishmaniasis, with careful consideration geared toward the species; for example, because our patient was infected with L panamensis, which is known to cause mucocutaneous disease, the infectious disease service decided to pursue systemic therapy with amphotericin B rather than topical treatment.

Prevention—Vector control is the primary means of preventing leishmaniasis under 2 umbrellas: environmental management and synthetic insecticides. The goal of environmental management is to eliminate the phlebotomine sandfly habitat; this was the primary method of vector control until 1940. Until that time, tree stumps were removed, indoor cracks and crevices were filled to prevent sandfly emergence, and areas around animal shelters were cleaned. These methods were highly dependent on community awareness and involvement; today, they can be combined with synthetic insecticides to offer maximum protection.

Synthetic insecticides include indoor sprays, treated nets, repellents, and impregnated dog collars, all of which control sandflies. However, the use of these insecticides in endemic areas, such as India, has driven development of insecticide resistance in many sandfly vector species.³

As of 2020, 5 vaccines against Leishmania have been created. Two are approved–one in Brazil and one in Uzbekistan–for human use as immunotherapy, while the other 3 have been developed to immunize dogs in Brazil. However, the effectiveness of these vaccines is under debate. First, one of the vaccines used as immunotherapy for cutaneous leishmaniasis must be used in combination with conventional chemotherapy; second, long-term effects of the canine vaccine are unknown.¹ A preventive vaccine for humans is under development.^1,3

Final Thoughts

Leishmaniasis remains a notable parasitic disease that is increasing in prevalence worldwide. Clinicians should be aware of this disease because early detection and treatment are essential to control infection.³ Health care providers in the United States should be especially aware of this condition among patients who have a history of travel or migration; those in Texas should recognize the current endemic status of leishmaniasis there.^4,6

The genus Leishmania comprises protozoan parasites that cause approximately 2 million new cases of leishmaniasis each year across 98 countries.¹ These protozoa are obligate intracellular parasites of phlebotomine sandfly species that transmit leishmaniasis and result in a considerable parasitic cause of fatalities globally, second only to malaria.^2,3

Phlebotomine sandflies primarily live in tropical and subtropical regions and function as vectors for many pathogens in addition to Leishmania species, such as Bartonella species and arboviruses.³ In 2004, it was noted that the majority of leishmaniasis cases affected developing countries: 90% of visceral leishmaniasis cases occurred in Bangladesh, India, Nepal, Sudan, and Brazil, and 90% of cutaneous leishmaniasis cases occurred in Afghanistan, Algeria, Brazil, Iran, Peru, Saudi Arabia, and Syria.⁴ Of note, with recent environmental changes, phlebotomine sandflies have gradually migrated to more northerly latitudes, extending into Europe.⁵

Twenty Leishmania species and 30 sandfly species have been identified as causes of leishmaniasis.⁴Leishmania infection occurs when an infected sandfly bites a mammalian host and transmits the parasite’s flagellated form, known as a promastigote. Host inflammatory cells, such as monocytes and dendritic cells, phagocytize parasites that enter the skin. The interaction between parasites and dendritic cells become an important factor in the outcome of Leishmania infection in the host because dendritic cells promote development of CD4 and CD8 T lymphocytes with specificity to target Leishmania parasites and protect the host.¹

The number of cases of leishmaniasis has increased worldwide, most likely due to changes in the environment and human behaviors such as urbanization, the creation of new settlements, and migration from rural to urban areas.^3,5 Important risk factors in individual patients include malnutrition; low-quality housing and sanitation; a history of migration or travel; and immunosuppression, such as that caused by HIV co-infection.^2,5

Case Report

An otherwise healthy 25-year-old Bangladeshi man presented to our community hospital for evaluation of a painful leg ulcer of 1 month’s duration. The patient had migrated from Bangladesh to Panama, then to Costa Rica, followed by Guatemala, Honduras, Mexico, and, last, Texas. In Texas, he was identified by the US Immigration and Customs Enforcement, transported to a detention facility, and transferred to this hospital shortly afterward.

The patient reported that, during his extensive migration, he had lived in the jungle and reported what he described as mosquito bites on the legs. He subsequently developed a 3-cm ulcerated and crusted plaque with rolled borders on the right medial ankle (Figure 1). In addition, he had a palpable nodular cord on the medial leg from the ankle lesion to the mid thigh that was consistent with lymphocutaneous spread. Ultrasonography was negative for deep-vein thrombosis.

CT112004016_e_Fig1_AB.jpg

Because the patient’s recent migration from Central America was highly concerning for microbial infection, vancomycin and piperacillin-tazobactam were started empirically on admission. A punch biopsy from the right medial ankle was nondiagnostic, showing acute and chronic necrotizing inflammation along with numerous epithelioid histiocytes with a vaguely granulomatous appearance (Figure 2). A specimen from the right medial ankle that had already been taken by an astute border patrol medical provider was sent to the Centers for Disease Control and Prevention (CDC) for polymerase chain reaction analysis following admission and was found to be positive for Leishmania panamensis.

CT112004016_e_Fig2_AB.jpg

Given the concern for mucocutaneous leishmaniasis with this particular species, otolaryngology was consulted; however, the patient did not demonstrate mucocutaneous disease. Because of the elevated risk for persistent disease with L panamensis, systemic therapy was indicated and administered: IV amphotericin B 200 mg on days 1 through 5 and again on day 10. Improvement in the ulcer was seen after the 10-day regimen was completed.

Comment

Leishmaniasis can be broadly classified by geographic region or clinical presentation. Under the geographic region system, leishmaniasis can be categorized as Old World or New World. Old World leishmaniasis primarily is transmitted by Phlebotomus sandflies and carries the parasites Leishmania major and Leishmania tropica, among others. New World leishmaniasis is caused by Lutzomyia sandflies, which carry Leishmania mexicana, Leishmania braziliensis, Leishmania amazonensis, and others.⁶

Our patient presented with cutaneous leishmaniasis, one of 4 primary clinical disease forms of leishmaniasis; the other 3 forms under this classification system are diffuse cutaneous, mucocutaneous, and visceral leishmaniasis, also known as kala-azar.^3,6 Cutaneous leishmaniasis is limited to the skin, particularly the face and extremities. This form is more common with Old World vectors, with most cases occurring in Peru, Brazil, and the Middle East. In Old World cutaneous leishmaniasis, the disease begins with a solitary nodule at the site of the bite that ulcerates and can continue to spread in a sporotrichoid pattern. This cutaneous form tends to heal slowly over months to years with residual scarring. New World cutaneous leishmaniasis can present with a variety of clinical manifestations, including ulcerative, sarcoidlike, miliary, and nodular lesions.^6,7

The diffuse form of cutaneous leishmaniasis begins in a similar manner to the Old World cutaneous form: a single nodule spreads widely over the body, especially the nose, and covers the patient’s skin with keloidal or verrucous lesions that do not ulcerate. These nodules contain large groupings of Leishmania-filled foamy macrophages. Often, patients with diffuse cutaneous leishmaniasis are immunosuppressed and are unable to develop an immune response to leishmanin and other skin antigens.^6,7

Mucocutaneous leishmaniasis predominantly is caused by the New World species L braziliensis but also has been attributed to L amazonensis, L panamensis, and L guyanensis. This form manifests as mucosal lesions that can develop simultaneously with cutaneous lesions but more commonly appear months to years after resolution of the skin infection. Patients often present with ulceration of the lip, nose, and oropharynx, and destruction of the nasopharynx can result in severe consequences such as obstruction of the airway and perforation of the nasal septum (also known as espundia).^6,7

The most severe presentation of leishmaniasis is the visceral form (kala-azar), which presents with parasitic infection of the liver, spleen, and bone marrow. Most commonly caused by Leishmania donovani, Leishmania infantum, and Leishmania chagasi, this form has a long incubation period spanning months to years before presenting with diarrhea, hepatomegaly, splenomegaly, darkening of the skin (in Hindi, kala-azar means “black fever”), pancytopenia, lymphadenopathy, nephritis, and intestinal hemorrhage, among other severe manifestations. Visceral leishmaniasis has a poor prognosis: patients succumb to disease within 2 years if not treated.^6,7

Diagnosis—Diagnosing leishmaniasis starts with a complete personal and medical history, paying close attention to travel and exposures. Diagnosis is most successfully performed by polymerase chain reaction analysis, which is both highly sensitive and specific but also can be determined by culture using Novy-McNeal-Nicolle medium or by light microscopy. Histologic findings include the marquee sign, which describes an array of amastigotes (promastigotes that have developed into the intracellular tissue-stage form) with kinetoplasts surrounding the periphery of parasitized histiocytes. Giemsa staining can be helpful in identifying organisms.^2,6,7

The diagnosis in our case was challenging, as none of the above findings were seen in our patient. The specimen taken by the border patrol medical provider was negative on Gram, Giemsa, and Grocott-Gömöri methenamine silver staining; no amastigotes were identified. Another diagnostic modality (not performed in our patient) is the Montenegro delayed skin-reaction test, which often is positive in patients with cutaneous leishmaniasis but also yields a positive result in patients who have been cured of Leishmania infection.⁶

An important consideration in the diagnostic workup of leishmaniasis is that collaboration with the CDC can be helpful, such as in our case, as they provide clear guidance for specimen collection and processing.²

Treatment—Treating leishmaniasis is challenging and complex. Even the initial decision to treat depends on several factors, including the form of infection. Most visceral and mucocutaneous infections should be treated due to both the lack of self-resolution of these forms and the higher risk for a potentially life-threatening disease course; in contrast, cutaneous forms require further consideration before initiating treatment. Some indicators for treating cutaneous leishmaniasis include widespread infection, intention to decrease scarring, and lesions with the potential to cause further complications (eg, on the face or ears or close to joints).^6-8

The treatment of choice for cutaneous and mucocutaneous leishmaniasis is pentavalent antimony; however, this drug can only be obtained in the United States for investigational use, requiring approval by the CDC. A 20-day intravenous or intramuscular course of 20 mg/kg per day typically is used for cutaneous cases; a 28-day course typically is used for mucosal forms.

Amphotericin B is not only the treatment of choice for visceral leishmaniasis but also is an important alternative therapy for patients with mucosal leishmaniasis or who are co-infected with HIV. Patients with visceral infection also should receive supportive care for any concomitant afflictions, such as malnutrition or other infections. Although different regimens have been described, the US Food and Drug Administration has created outlines of specific intravenous infusion schedules for liposomal amphotericin B in immunocompetent and immunosuppressed patients.⁸ Liposomal amphotericin B also has a more favorable toxicity profile than conventional amphotericin B deoxycholate, which is otherwise effective in combating visceral leishmaniasis.^6-8

Other treatments that have been attempted include pentamidine, miltefosine, thermotherapy, oral itraconazole and fluconazole, rifampicin, metronidazole and cotrimoxazole, dapsone, photodynamic therapy, thermotherapy, topical paromomycin formulations, intralesional pentavalent antimony, and laser cryotherapy. Notable among these other agents is miltefosine, a US Food and Drug Administration–approved oral medication for adults and adolescents (used off-label for patients younger than 12 years) with cutaneous leishmaniasis caused by L braziliensis, L panamensis, or L guyanensis. Other oral options mentioned include the so-called azole antifungal medications, which historically have produced variable results. From the CDC’s reports, ketoconazole was moderately effective in Guatemala and Panama,⁸ whereas itraconazole did not demonstrate efficacy in Colombia, and the efficacy of fluconazole was inconsistent in different countries.⁸ When considering one of the local (as opposed to oral and parenteral) therapies mentioned, the extent of cutaneous findings as well as the risk of mucosal spread should be factored in.^6-8

Understandably, a number of considerations can come into play in determining the appropriate treatment modality, including body region affected, clinical form, severity, and Leishmania species.^6-8 Our case is of particular interest because it demonstrates the complexities behind the diagnosis and treatment of cutaneous leishmaniasis, with careful consideration geared toward the species; for example, because our patient was infected with L panamensis, which is known to cause mucocutaneous disease, the infectious disease service decided to pursue systemic therapy with amphotericin B rather than topical treatment.

Prevention—Vector control is the primary means of preventing leishmaniasis under 2 umbrellas: environmental management and synthetic insecticides. The goal of environmental management is to eliminate the phlebotomine sandfly habitat; this was the primary method of vector control until 1940. Until that time, tree stumps were removed, indoor cracks and crevices were filled to prevent sandfly emergence, and areas around animal shelters were cleaned. These methods were highly dependent on community awareness and involvement; today, they can be combined with synthetic insecticides to offer maximum protection.

Synthetic insecticides include indoor sprays, treated nets, repellents, and impregnated dog collars, all of which control sandflies. However, the use of these insecticides in endemic areas, such as India, has driven development of insecticide resistance in many sandfly vector species.³

As of 2020, 5 vaccines against Leishmania have been created. Two are approved–one in Brazil and one in Uzbekistan–for human use as immunotherapy, while the other 3 have been developed to immunize dogs in Brazil. However, the effectiveness of these vaccines is under debate. First, one of the vaccines used as immunotherapy for cutaneous leishmaniasis must be used in combination with conventional chemotherapy; second, long-term effects of the canine vaccine are unknown.¹ A preventive vaccine for humans is under development.^1,3

Final Thoughts

Leishmaniasis remains a notable parasitic disease that is increasing in prevalence worldwide. Clinicians should be aware of this disease because early detection and treatment are essential to control infection.³ Health care providers in the United States should be especially aware of this condition among patients who have a history of travel or migration; those in Texas should recognize the current endemic status of leishmaniasis there.^4,6

Incidence and Characteristics

The noble false widow spider (Steatoda nobilis) is one of the world’s most invasive spider species, having spread across the globe from Madeira and the Canary Islands into the North Atlantic.^1,2Steatoda comprise multiple species of false widow spiders, named for their resemblance to black widow spiders (Latrodectus). The noble false widow spider is the dominant species in buildings in southern Ireland and Great Britain, with a population surge in 2018 that caused multiple temporary school closures in London, England, for fumigation.³ The noble false widow spider was first documented in the United States in Ventura County, California, in 2011, with numerous specimens found in urban areas (eg, in parks, underneath garbage cans) closer to the coastline as well as farther inland. The species may have been introduced to this area by way of Port Hueneme, a city in California with a US naval base with routes to various other military bases in Western Europe.⁴ Given its already rapid expansion outside of the United States with a concurrent rise in bite reports, dermatologists should be familiar with these invasive and potentially dangerous arachnids.

The spread of noble false widow spiders is assisted by their wide range of temperature tolerance and ability to survive for months with little food and no water. They can live for several years, with one report of a noble false widow spider living up to 7 years.⁵ These spiders are found inside homes and buildings year-round, and they prefer to build their webs in an elevated position such as the top corner of a room. Steatoda weave tangle webs with crisscrossing threads that often have a denser middle section.⁵

Noble false widow spiders are sexually dimorphic, with males typically no larger than 1-cm long and females up to 1.4-cm long. They have a dark brown to black thorax and brown abdomen with red-brown legs. Males have brighter cream-colored abdominal markings than females, who lack markings altogether on their distinctive globular abdomen (Figure). The abdominal markings are known to resemble a skull or house.

Johnson1_getty_figure.jpg

Although noble false widow spiders are not exclusively synanthropic, they can be found in any crevice in homes or other structures where there are humans such as office buildings.^5-7 Up until the last 20 years, reports of bites from noble false widow spiders worldwide were few and far between. In Great Britain, the spiders were first considered to be common in the 1980s, with recent evidence of an urban population boom in the last 5 to 10 years that has coincided with an increase in bite reports.^5,8,9

Clinical Significance

Most bites occur in a defensive manner, such as when humans perform activities that disturb the hiding space, cause vibrations in the web, or compress the body of the arachnid. Most envenomations in Great Britain occur while the individual is in bed, though they also may occur during other activities that disturb the spider, such as moving boxes or putting on a pair of pants.⁵ Occupational exposure to noble false widow spiders may soon be a concern for those involved in construction, carpentry, cleaning, and decorating given their recent invasive spread into the United States.

The venom from these spiders is neurotoxic and cytotoxic, causing moderate to intense pain that may resemble a wasp sting. The incidence of steatodism—which can include symptoms of pain in addition to fever, hypotension, headache, lethargy, nausea, localized diaphoresis, abdominal pain, paresthesias, and malaise—is unknown but reportedly rare.^5,10 There are considerable similarities between Steatoda and true black widow spider venom, which explains the symptom overlap with latrodectism. There are reports of severe debilitation lasting weeks due to pain and decreased affected limb movement after bites from noble false widow spiders.^10-12

Nearly all noble false widow spider bite reports describe immediate pain upon bite/envenomation, which is unlike the delayed pain from a black widow spider bite (after 10 minutes or more).^6,13,14 Erythema and swelling occur around a pale raised site of envenomation lasting up to 72 hours. The bite site may be highly tender and blister or ulcerate, with reports of cellulitis and local skin necrosis.^7,15 Pruritus during this period can be intense, and excoriation increases the risk for complications such as infection. Reports of anaphylaxis following a noble false widow spider bite are rare.^5,16 The incidence of bites may be underreported due to the lack of proper identification of the responsible arachnid for those who do not seek care or require hospitalization, though this is not unique to Steatoda.

There are reports of secondary infection after bites and even cases of limb amputation, septicemia, and death.^14,17 However, it is unknown if noble false widow spiders are vectors for bacteria transmitted during envenomation, and infection likely is secondary to scratching or inadequate wound care.^18,19 Potentially pathogenic bacteria have been isolated from the body surfaces of the noble false widow spider, including Pseudomonas putida, Staphylococcus capitis, and Staphylococcus epidermidis.²⁰ Fortunately, most captured cases (ie, events in which the biting arachnid was properly identified) report symptoms ranging from mild to moderate in severity without the need for hospitalization. A series of 24 reports revealed that all individuals experienced sharp pain upon the initial bite followed by erythema, and 18 of them experienced considerable swelling of the area soon thereafter. One individual experienced temporary paralysis of the affected limb, and 3 individuals experienced hypotension or hypertension in addition to fever, skin necrosis, or cellulitis.¹⁴

Treatment

The envenomation site should be washed with antibacterial soap and warm water and should be kept clean to prevent infection. There is no evidence that tight pressure bandaging of these bite sites will restrict venom flow; because it may worsen pain in the area, pressure bandaging is not recommended. When possible, the arachnid should be collected for identification. Supportive care is warranted for symptoms of pain, erythema, and swelling, with the use of cool compresses, oral pain relievers (eg, nonsteroidal anti-inflammatory drugs, acetaminophen), topical anesthetic (eg, lidocaine), or antihistamines as needed.

Urgent care is warranted for patients who experience severe symptoms of steatodism such as hypertension, lymphadenopathy, paresthesia, or limb paralysis. Limited reports show onset of this distress typically within an hour of envenomation. Treatments analogous to those for latrodectism including muscle relaxers and pain medications have demonstrated rapid attenuation of symptoms upon intramuscular administration of antivenom made from Latrodectus species.^21-23

Signs of infection warrant bacterial culture with antibiotic susceptibilities to ensure adequate treatment.²⁰ Infections from spider bites can present a few days to a week following envenomation. Symptoms may include spreading redness or an enlarging wound site, pus formation, worsening or unrelenting pain after 24 hours, fevers, flulike symptoms, and muscle cramps.

Final Thoughts

Symptoms from noble false widow spider bites range widely from localized pain, swelling, and erythema to ulceration, necrosis, and rarely death related to secondary infection. Because of their invasive spread in Europe and increasing presence in the United States, it is important to be aware of the possibility of noble false widow spider bites to manage reactions that may quickly lead to morbidity.

Incidence and Characteristics

The noble false widow spider (Steatoda nobilis) is one of the world’s most invasive spider species, having spread across the globe from Madeira and the Canary Islands into the North Atlantic.^1,2Steatoda comprise multiple species of false widow spiders, named for their resemblance to black widow spiders (Latrodectus). The noble false widow spider is the dominant species in buildings in southern Ireland and Great Britain, with a population surge in 2018 that caused multiple temporary school closures in London, England, for fumigation.³ The noble false widow spider was first documented in the United States in Ventura County, California, in 2011, with numerous specimens found in urban areas (eg, in parks, underneath garbage cans) closer to the coastline as well as farther inland. The species may have been introduced to this area by way of Port Hueneme, a city in California with a US naval base with routes to various other military bases in Western Europe.⁴ Given its already rapid expansion outside of the United States with a concurrent rise in bite reports, dermatologists should be familiar with these invasive and potentially dangerous arachnids.

The spread of noble false widow spiders is assisted by their wide range of temperature tolerance and ability to survive for months with little food and no water. They can live for several years, with one report of a noble false widow spider living up to 7 years.⁵ These spiders are found inside homes and buildings year-round, and they prefer to build their webs in an elevated position such as the top corner of a room. Steatoda weave tangle webs with crisscrossing threads that often have a denser middle section.⁵

Noble false widow spiders are sexually dimorphic, with males typically no larger than 1-cm long and females up to 1.4-cm long. They have a dark brown to black thorax and brown abdomen with red-brown legs. Males have brighter cream-colored abdominal markings than females, who lack markings altogether on their distinctive globular abdomen (Figure). The abdominal markings are known to resemble a skull or house.

Johnson1_getty_figure.jpg

Although noble false widow spiders are not exclusively synanthropic, they can be found in any crevice in homes or other structures where there are humans such as office buildings.^5-7 Up until the last 20 years, reports of bites from noble false widow spiders worldwide were few and far between. In Great Britain, the spiders were first considered to be common in the 1980s, with recent evidence of an urban population boom in the last 5 to 10 years that has coincided with an increase in bite reports.^5,8,9

Clinical Significance

Most bites occur in a defensive manner, such as when humans perform activities that disturb the hiding space, cause vibrations in the web, or compress the body of the arachnid. Most envenomations in Great Britain occur while the individual is in bed, though they also may occur during other activities that disturb the spider, such as moving boxes or putting on a pair of pants.⁵ Occupational exposure to noble false widow spiders may soon be a concern for those involved in construction, carpentry, cleaning, and decorating given their recent invasive spread into the United States.

The venom from these spiders is neurotoxic and cytotoxic, causing moderate to intense pain that may resemble a wasp sting. The incidence of steatodism—which can include symptoms of pain in addition to fever, hypotension, headache, lethargy, nausea, localized diaphoresis, abdominal pain, paresthesias, and malaise—is unknown but reportedly rare.^5,10 There are considerable similarities between Steatoda and true black widow spider venom, which explains the symptom overlap with latrodectism. There are reports of severe debilitation lasting weeks due to pain and decreased affected limb movement after bites from noble false widow spiders.^10-12

Nearly all noble false widow spider bite reports describe immediate pain upon bite/envenomation, which is unlike the delayed pain from a black widow spider bite (after 10 minutes or more).^6,13,14 Erythema and swelling occur around a pale raised site of envenomation lasting up to 72 hours. The bite site may be highly tender and blister or ulcerate, with reports of cellulitis and local skin necrosis.^7,15 Pruritus during this period can be intense, and excoriation increases the risk for complications such as infection. Reports of anaphylaxis following a noble false widow spider bite are rare.^5,16 The incidence of bites may be underreported due to the lack of proper identification of the responsible arachnid for those who do not seek care or require hospitalization, though this is not unique to Steatoda.

There are reports of secondary infection after bites and even cases of limb amputation, septicemia, and death.^14,17 However, it is unknown if noble false widow spiders are vectors for bacteria transmitted during envenomation, and infection likely is secondary to scratching or inadequate wound care.^18,19 Potentially pathogenic bacteria have been isolated from the body surfaces of the noble false widow spider, including Pseudomonas putida, Staphylococcus capitis, and Staphylococcus epidermidis.²⁰ Fortunately, most captured cases (ie, events in which the biting arachnid was properly identified) report symptoms ranging from mild to moderate in severity without the need for hospitalization. A series of 24 reports revealed that all individuals experienced sharp pain upon the initial bite followed by erythema, and 18 of them experienced considerable swelling of the area soon thereafter. One individual experienced temporary paralysis of the affected limb, and 3 individuals experienced hypotension or hypertension in addition to fever, skin necrosis, or cellulitis.¹⁴

Treatment

The envenomation site should be washed with antibacterial soap and warm water and should be kept clean to prevent infection. There is no evidence that tight pressure bandaging of these bite sites will restrict venom flow; because it may worsen pain in the area, pressure bandaging is not recommended. When possible, the arachnid should be collected for identification. Supportive care is warranted for symptoms of pain, erythema, and swelling, with the use of cool compresses, oral pain relievers (eg, nonsteroidal anti-inflammatory drugs, acetaminophen), topical anesthetic (eg, lidocaine), or antihistamines as needed.

Urgent care is warranted for patients who experience severe symptoms of steatodism such as hypertension, lymphadenopathy, paresthesia, or limb paralysis. Limited reports show onset of this distress typically within an hour of envenomation. Treatments analogous to those for latrodectism including muscle relaxers and pain medications have demonstrated rapid attenuation of symptoms upon intramuscular administration of antivenom made from Latrodectus species.^21-23

Signs of infection warrant bacterial culture with antibiotic susceptibilities to ensure adequate treatment.²⁰ Infections from spider bites can present a few days to a week following envenomation. Symptoms may include spreading redness or an enlarging wound site, pus formation, worsening or unrelenting pain after 24 hours, fevers, flulike symptoms, and muscle cramps.

Final Thoughts

Symptoms from noble false widow spider bites range widely from localized pain, swelling, and erythema to ulceration, necrosis, and rarely death related to secondary infection. Because of their invasive spread in Europe and increasing presence in the United States, it is important to be aware of the possibility of noble false widow spider bites to manage reactions that may quickly lead to morbidity.

Incidence and Characteristics

The noble false widow spider (Steatoda nobilis) is one of the world’s most invasive spider species, having spread across the globe from Madeira and the Canary Islands into the North Atlantic.^1,2Steatoda comprise multiple species of false widow spiders, named for their resemblance to black widow spiders (Latrodectus). The noble false widow spider is the dominant species in buildings in southern Ireland and Great Britain, with a population surge in 2018 that caused multiple temporary school closures in London, England, for fumigation.³ The noble false widow spider was first documented in the United States in Ventura County, California, in 2011, with numerous specimens found in urban areas (eg, in parks, underneath garbage cans) closer to the coastline as well as farther inland. The species may have been introduced to this area by way of Port Hueneme, a city in California with a US naval base with routes to various other military bases in Western Europe.⁴ Given its already rapid expansion outside of the United States with a concurrent rise in bite reports, dermatologists should be familiar with these invasive and potentially dangerous arachnids.

The spread of noble false widow spiders is assisted by their wide range of temperature tolerance and ability to survive for months with little food and no water. They can live for several years, with one report of a noble false widow spider living up to 7 years.⁵ These spiders are found inside homes and buildings year-round, and they prefer to build their webs in an elevated position such as the top corner of a room. Steatoda weave tangle webs with crisscrossing threads that often have a denser middle section.⁵

Noble false widow spiders are sexually dimorphic, with males typically no larger than 1-cm long and females up to 1.4-cm long. They have a dark brown to black thorax and brown abdomen with red-brown legs. Males have brighter cream-colored abdominal markings than females, who lack markings altogether on their distinctive globular abdomen (Figure). The abdominal markings are known to resemble a skull or house.

Johnson1_getty_figure.jpg

Although noble false widow spiders are not exclusively synanthropic, they can be found in any crevice in homes or other structures where there are humans such as office buildings.^5-7 Up until the last 20 years, reports of bites from noble false widow spiders worldwide were few and far between. In Great Britain, the spiders were first considered to be common in the 1980s, with recent evidence of an urban population boom in the last 5 to 10 years that has coincided with an increase in bite reports.^5,8,9

Clinical Significance

Most bites occur in a defensive manner, such as when humans perform activities that disturb the hiding space, cause vibrations in the web, or compress the body of the arachnid. Most envenomations in Great Britain occur while the individual is in bed, though they also may occur during other activities that disturb the spider, such as moving boxes or putting on a pair of pants.⁵ Occupational exposure to noble false widow spiders may soon be a concern for those involved in construction, carpentry, cleaning, and decorating given their recent invasive spread into the United States.

The venom from these spiders is neurotoxic and cytotoxic, causing moderate to intense pain that may resemble a wasp sting. The incidence of steatodism—which can include symptoms of pain in addition to fever, hypotension, headache, lethargy, nausea, localized diaphoresis, abdominal pain, paresthesias, and malaise—is unknown but reportedly rare.^5,10 There are considerable similarities between Steatoda and true black widow spider venom, which explains the symptom overlap with latrodectism. There are reports of severe debilitation lasting weeks due to pain and decreased affected limb movement after bites from noble false widow spiders.^10-12

Nearly all noble false widow spider bite reports describe immediate pain upon bite/envenomation, which is unlike the delayed pain from a black widow spider bite (after 10 minutes or more).^6,13,14 Erythema and swelling occur around a pale raised site of envenomation lasting up to 72 hours. The bite site may be highly tender and blister or ulcerate, with reports of cellulitis and local skin necrosis.^7,15 Pruritus during this period can be intense, and excoriation increases the risk for complications such as infection. Reports of anaphylaxis following a noble false widow spider bite are rare.^5,16 The incidence of bites may be underreported due to the lack of proper identification of the responsible arachnid for those who do not seek care or require hospitalization, though this is not unique to Steatoda.

There are reports of secondary infection after bites and even cases of limb amputation, septicemia, and death.^14,17 However, it is unknown if noble false widow spiders are vectors for bacteria transmitted during envenomation, and infection likely is secondary to scratching or inadequate wound care.^18,19 Potentially pathogenic bacteria have been isolated from the body surfaces of the noble false widow spider, including Pseudomonas putida, Staphylococcus capitis, and Staphylococcus epidermidis.²⁰ Fortunately, most captured cases (ie, events in which the biting arachnid was properly identified) report symptoms ranging from mild to moderate in severity without the need for hospitalization. A series of 24 reports revealed that all individuals experienced sharp pain upon the initial bite followed by erythema, and 18 of them experienced considerable swelling of the area soon thereafter. One individual experienced temporary paralysis of the affected limb, and 3 individuals experienced hypotension or hypertension in addition to fever, skin necrosis, or cellulitis.¹⁴

Treatment

The envenomation site should be washed with antibacterial soap and warm water and should be kept clean to prevent infection. There is no evidence that tight pressure bandaging of these bite sites will restrict venom flow; because it may worsen pain in the area, pressure bandaging is not recommended. When possible, the arachnid should be collected for identification. Supportive care is warranted for symptoms of pain, erythema, and swelling, with the use of cool compresses, oral pain relievers (eg, nonsteroidal anti-inflammatory drugs, acetaminophen), topical anesthetic (eg, lidocaine), or antihistamines as needed.

Urgent care is warranted for patients who experience severe symptoms of steatodism such as hypertension, lymphadenopathy, paresthesia, or limb paralysis. Limited reports show onset of this distress typically within an hour of envenomation. Treatments analogous to those for latrodectism including muscle relaxers and pain medications have demonstrated rapid attenuation of symptoms upon intramuscular administration of antivenom made from Latrodectus species.^21-23

Signs of infection warrant bacterial culture with antibiotic susceptibilities to ensure adequate treatment.²⁰ Infections from spider bites can present a few days to a week following envenomation. Symptoms may include spreading redness or an enlarging wound site, pus formation, worsening or unrelenting pain after 24 hours, fevers, flulike symptoms, and muscle cramps.

Final Thoughts

Symptoms from noble false widow spider bites range widely from localized pain, swelling, and erythema to ulceration, necrosis, and rarely death related to secondary infection. Because of their invasive spread in Europe and increasing presence in the United States, it is important to be aware of the possibility of noble false widow spider bites to manage reactions that may quickly lead to morbidity.

The tropical rat mite (Ornithonyssus bacoti) belongs to the family Macronyssidae. Theses mites are commonly mistaken for red bird mites or Nordic bird mites because they belong to the same family and have similar characteristics.¹ Although O bacoti is called the tropical rat mite, it also can be found in moderate climates.^2,3

Characteristics

The life cycle of a tropical rat mite lasts 11 to 13 days and includes 5 stages: egg, larva, protonymph, deutonymph, and adult.^1,2 The length of the mite (0.3–0.7 mm) varies with the stage of development.¹ Adults can reach 0.75 to 1.40 mm, with females larger than males and possibly visible with the naked eye.^1,2

Two or 3 days after a blood meal, the female mite lays approximately 100 eggs in its nest but not on the surface of a host. The eggs hatch into larvae after 1 to 4 days and go on to complete their life cyle.¹ During developmental stages, mites occupy their hosts for blood meals. Mites search for their hosts at night and prefer wild or pet rodents for blood meals but are not host specific and can be found on many mammals including birds, cats, racoons, and squirrels.⁴

Although tropical rat mites prefer rodent hosts, they can infest humans when their preferred host is unavailable. In the United States, the first case of human dermatitis due to a tropical rate mite occurred in 1923. In Europe, rat mite dermatitis was first reported in a human in 1931, possibly due to contamination of sailing vessels.⁴

Infestation and Transmission

Tropical rat mites prefer wild and pet rodents as hosts because the mites are able to feed on their blood over long periods.⁴ During the day, the mite spends most of its time hiding in dark dry spaces; it is most active during the night, traveling to find a host for meals.^3-5 If a preferred host is not present, the mite may choose to infest a human.⁵

Human infestation occurs most often upon close bodily contact with an infected animal or pet rodent that was sold without parasites having been eliminated.^3-5 Mites are able to survive without a host for as long as 6 months; they may travel after a meal.^1,2 Therefore, individuals who do not have a pet rodent can be infested if an infected wild rodent has infested their living space.^1,3-5

Clinical Presentation of Infestation

Patients infested with tropical rat mites present with pruritic cutaneous lesions, most often on unclothed parts of the body that are easily exposed to mites; lesions rarely occur on the scalp.⁵ People of any age or gender can be infested. Rat mite bites can present as single or grouped, pruritic, erythematous papules ranging in size from 4 to 10 mm in diameter.^5-7 Excoriations may be present due to excessive scratching. Although rare, vesicles or nodules have been reported.^5,7

Diagnosis of the underlying cause of the cutaneous manifestations often is difficult because mites are not visible during the day, as they are less active then.² Lesions often are misdiagnosed as an allergic response, a bacterial infection, or various forms of dermatitis.¹ A parasitic cause often is not considered unless the physician or patient detects a mite or many trials of therapies fail to provide relief.^1,3-5 Eliciting a thorough history may disclose that the patient has had close contact with rodents or lives in a community center, shelter, or shared space. If any of the patient’s close contacts have a similar presentation, infestation with mites should be considered.

Patients should be educated about treatment options and measures that need to be taken to prevent reinfection. It has been reported that tropical rat mites can survive without a blood meal for as long as 6 months; therefore, meticulous inspection and decontamination of all living spaces is required.^1,4 Once identified, physicians may prescribe an antiparasitic such as permethrin or pyriproxyfen to prevent further infestation and eliminate mites on the host.⁵ Lindane and benzyl benzoate previously were reported to be effective but should be prescribed only in correctly diagnosed cases due to the potential adverse effects of both therapies.^4,7-10 For effective treatment, physicians should thoroughly review the proper application of topical treatments with patients. Topical creams should be massaged into the skin from the head to the soles of the feet, covering all creases of the skin and between the fingers and toes. Antiparasitic creams should be left on the skin for 8 to 14 hours, and all members of the household should be examined and treated, if necessary, by a physician. A thorough bath removes tropical rat mites, but preventive measures should be taken to prevent reinfestation.⁴ Antihistamines or glucocorticoids also can be used as symptomatic treatment.^6,8

Avoiding Reinfestation—Preventive measures should be taken to prevent reinfestation, including evaluation by an exterminator for any wild rodents to remove nests and treat the living space with an acaricide.⁵ Insecticides administered by exterminators, including malathion, methyl carbamate, and lindane, also have been reported to be effective for preventing reinfestation.^5,7-9 A veterinarian should be consulted if the patient owns any pets to ensure proper identification of any potential tropical rat mites and treatments that may be necessary for any household pets.¹

Case Report

A 68-year-old man presented to the dermatology outpatient clinic with diffuse pruritus of the skin and scalp. He reported no other symptoms and had never had a total-body skin examination. His primary care physician recently prescribed a dose pack of methylprednisolone 4-mg tablets, which relieved the symptoms except for a mild scalp itch. His wife did not experience itching, and he denied noticing mites or fleas on his pet dog. Physical examination did not reveal any contributory findings, such as erythema or rash. Ketoconazole shampoo 2% and fluocinolone solution 0.01% were prescribed for scalp pruritus; however, he could not afford those medications and therefore did not take them.

Two weeks later, the patient presented with diffuse itching that involved the scalp, trunk, and extremities. He denied groin pruritus. He reported that the itching was worse at night. His wife continued to be asymptomatic. The patient reported that his health screening was up-to-date, and he had no interval health changes. A complete blood cell count, thyroid studies, and a comprehensive metabolic panel performed recently were within reference range. He denied recent travel or taking new medications. Physical examination revealed a somewhat linear distribution of erythematous urticarial papules on the right side of the abdomen. Red dermatographic excoriations were noted on the back. No burrows were visualized. He was given intramuscular triamcinolone 60 mg and was advised to have his house evaluated for bed bugs and his pet dog evaluated by a veterinarian for mites. During the triamcinolone injection, the medical assistant observed a 1- to 2-mm red insect, which fell into his clothing and could not be further evaluated.

After 1 month, the patient had no improvement of the pruritus; instead, it became worse. During this time, his wife developed intermittent urticarial-like eruptions. He was taking oral diphenhydramine nightly and applying triamcinolone cream 0.5% that he had at home from an earlier skin problem as needed. Physical examination findings correlated with worsening symptoms. He had multiple erythematous urticarial papules—many of which were excoriated—across the chest, abdomen, buttocks, and back. The arms had multiple excoriations. The urticarial papules coalesced in the anterior axillary folds, yet no burrows were visualized. In the left anterior axillary fold adjacent to one of the urticarial papules, a 1-mm mobile mite was identified on dermoscopy. Further evaluation by microscopy showed morphologic characteristics of a tropical rat mite (Figure). The patient admitted that his house had a mouse infestation that he was struggling to eliminate. Permethrin cream 5% was prescribed. Because the patient could not afford the prescription, he was advised to use the triamcinolone cream 0.5%and oral diphenhydramine that he had at home nightly for symptomatic relief. He was advised to hire an exterminator to eradicate the mouse and mite infestation to prevent reinfestation.

Yousif.jpg

Identification of Rate Mite Dermatitis

The characteristics of tropical rat mite dermatitis can be confused with many other conditions, such as infection. Even when a mite is identified, it can be difficult to classify it as a tropical rat mite. To confirm the diagnosis of tropical rat mite dermatitis, the parasite needs to be identified. Skin scrapings can be collected from pruritic lesions and examined microscopically in the hope of revealing the rat mites. The recommendation is to collect skin scrapings from the dorsal aspect of the hands or from the neck.⁵ Patients may report finding mites in their living space or on their bedding or clothing.

Although the tropical rat mite was reported as a vector for endemic typhus between humans, no other cases of transmission between humans have been reported since.^11,12 Studies reporting non–human subject research and case reports have shown that O bacoti is a vector for Rickettsia akari, Coxiella burnetii, Francisella tularensis, Yersinia pestis, Eastern equine encephalitis virus (Alphavirus), Enterovirus (Picornaviridae), Langat virus (Flavivirus), and Hantaan orthohantavirus.^5,11-17 However, no cases of these infectious diseases being transmitted naturally have been reported.⁵

Confirmation of O bacoti as a vector for human pathogens is difficult because it relies on identification of the mite in the clinic.⁵ The epidemiologic importance of the mite in transmitting infectious disease is unknown; reports of human cases of mite infestation are rare. We present this information to increase awareness and help dermatologists and other health care providers identify O bacoti.

The tropical rat mite (Ornithonyssus bacoti) belongs to the family Macronyssidae. Theses mites are commonly mistaken for red bird mites or Nordic bird mites because they belong to the same family and have similar characteristics.¹ Although O bacoti is called the tropical rat mite, it also can be found in moderate climates.^2,3

Characteristics

The life cycle of a tropical rat mite lasts 11 to 13 days and includes 5 stages: egg, larva, protonymph, deutonymph, and adult.^1,2 The length of the mite (0.3–0.7 mm) varies with the stage of development.¹ Adults can reach 0.75 to 1.40 mm, with females larger than males and possibly visible with the naked eye.^1,2

Two or 3 days after a blood meal, the female mite lays approximately 100 eggs in its nest but not on the surface of a host. The eggs hatch into larvae after 1 to 4 days and go on to complete their life cyle.¹ During developmental stages, mites occupy their hosts for blood meals. Mites search for their hosts at night and prefer wild or pet rodents for blood meals but are not host specific and can be found on many mammals including birds, cats, racoons, and squirrels.⁴

Although tropical rat mites prefer rodent hosts, they can infest humans when their preferred host is unavailable. In the United States, the first case of human dermatitis due to a tropical rate mite occurred in 1923. In Europe, rat mite dermatitis was first reported in a human in 1931, possibly due to contamination of sailing vessels.⁴

Infestation and Transmission

Tropical rat mites prefer wild and pet rodents as hosts because the mites are able to feed on their blood over long periods.⁴ During the day, the mite spends most of its time hiding in dark dry spaces; it is most active during the night, traveling to find a host for meals.^3-5 If a preferred host is not present, the mite may choose to infest a human.⁵

Human infestation occurs most often upon close bodily contact with an infected animal or pet rodent that was sold without parasites having been eliminated.^3-5 Mites are able to survive without a host for as long as 6 months; they may travel after a meal.^1,2 Therefore, individuals who do not have a pet rodent can be infested if an infected wild rodent has infested their living space.^1,3-5

Clinical Presentation of Infestation

Patients infested with tropical rat mites present with pruritic cutaneous lesions, most often on unclothed parts of the body that are easily exposed to mites; lesions rarely occur on the scalp.⁵ People of any age or gender can be infested. Rat mite bites can present as single or grouped, pruritic, erythematous papules ranging in size from 4 to 10 mm in diameter.^5-7 Excoriations may be present due to excessive scratching. Although rare, vesicles or nodules have been reported.^5,7

Diagnosis of the underlying cause of the cutaneous manifestations often is difficult because mites are not visible during the day, as they are less active then.² Lesions often are misdiagnosed as an allergic response, a bacterial infection, or various forms of dermatitis.¹ A parasitic cause often is not considered unless the physician or patient detects a mite or many trials of therapies fail to provide relief.^1,3-5 Eliciting a thorough history may disclose that the patient has had close contact with rodents or lives in a community center, shelter, or shared space. If any of the patient’s close contacts have a similar presentation, infestation with mites should be considered.

Patients should be educated about treatment options and measures that need to be taken to prevent reinfection. It has been reported that tropical rat mites can survive without a blood meal for as long as 6 months; therefore, meticulous inspection and decontamination of all living spaces is required.^1,4 Once identified, physicians may prescribe an antiparasitic such as permethrin or pyriproxyfen to prevent further infestation and eliminate mites on the host.⁵ Lindane and benzyl benzoate previously were reported to be effective but should be prescribed only in correctly diagnosed cases due to the potential adverse effects of both therapies.^4,7-10 For effective treatment, physicians should thoroughly review the proper application of topical treatments with patients. Topical creams should be massaged into the skin from the head to the soles of the feet, covering all creases of the skin and between the fingers and toes. Antiparasitic creams should be left on the skin for 8 to 14 hours, and all members of the household should be examined and treated, if necessary, by a physician. A thorough bath removes tropical rat mites, but preventive measures should be taken to prevent reinfestation.⁴ Antihistamines or glucocorticoids also can be used as symptomatic treatment.^6,8

Avoiding Reinfestation—Preventive measures should be taken to prevent reinfestation, including evaluation by an exterminator for any wild rodents to remove nests and treat the living space with an acaricide.⁵ Insecticides administered by exterminators, including malathion, methyl carbamate, and lindane, also have been reported to be effective for preventing reinfestation.^5,7-9 A veterinarian should be consulted if the patient owns any pets to ensure proper identification of any potential tropical rat mites and treatments that may be necessary for any household pets.¹

Case Report

A 68-year-old man presented to the dermatology outpatient clinic with diffuse pruritus of the skin and scalp. He reported no other symptoms and had never had a total-body skin examination. His primary care physician recently prescribed a dose pack of methylprednisolone 4-mg tablets, which relieved the symptoms except for a mild scalp itch. His wife did not experience itching, and he denied noticing mites or fleas on his pet dog. Physical examination did not reveal any contributory findings, such as erythema or rash. Ketoconazole shampoo 2% and fluocinolone solution 0.01% were prescribed for scalp pruritus; however, he could not afford those medications and therefore did not take them.

Two weeks later, the patient presented with diffuse itching that involved the scalp, trunk, and extremities. He denied groin pruritus. He reported that the itching was worse at night. His wife continued to be asymptomatic. The patient reported that his health screening was up-to-date, and he had no interval health changes. A complete blood cell count, thyroid studies, and a comprehensive metabolic panel performed recently were within reference range. He denied recent travel or taking new medications. Physical examination revealed a somewhat linear distribution of erythematous urticarial papules on the right side of the abdomen. Red dermatographic excoriations were noted on the back. No burrows were visualized. He was given intramuscular triamcinolone 60 mg and was advised to have his house evaluated for bed bugs and his pet dog evaluated by a veterinarian for mites. During the triamcinolone injection, the medical assistant observed a 1- to 2-mm red insect, which fell into his clothing and could not be further evaluated.

After 1 month, the patient had no improvement of the pruritus; instead, it became worse. During this time, his wife developed intermittent urticarial-like eruptions. He was taking oral diphenhydramine nightly and applying triamcinolone cream 0.5% that he had at home from an earlier skin problem as needed. Physical examination findings correlated with worsening symptoms. He had multiple erythematous urticarial papules—many of which were excoriated—across the chest, abdomen, buttocks, and back. The arms had multiple excoriations. The urticarial papules coalesced in the anterior axillary folds, yet no burrows were visualized. In the left anterior axillary fold adjacent to one of the urticarial papules, a 1-mm mobile mite was identified on dermoscopy. Further evaluation by microscopy showed morphologic characteristics of a tropical rat mite (Figure). The patient admitted that his house had a mouse infestation that he was struggling to eliminate. Permethrin cream 5% was prescribed. Because the patient could not afford the prescription, he was advised to use the triamcinolone cream 0.5%and oral diphenhydramine that he had at home nightly for symptomatic relief. He was advised to hire an exterminator to eradicate the mouse and mite infestation to prevent reinfestation.

Yousif.jpg

Identification of Rate Mite Dermatitis

The characteristics of tropical rat mite dermatitis can be confused with many other conditions, such as infection. Even when a mite is identified, it can be difficult to classify it as a tropical rat mite. To confirm the diagnosis of tropical rat mite dermatitis, the parasite needs to be identified. Skin scrapings can be collected from pruritic lesions and examined microscopically in the hope of revealing the rat mites. The recommendation is to collect skin scrapings from the dorsal aspect of the hands or from the neck.⁵ Patients may report finding mites in their living space or on their bedding or clothing.

Although the tropical rat mite was reported as a vector for endemic typhus between humans, no other cases of transmission between humans have been reported since.^11,12 Studies reporting non–human subject research and case reports have shown that O bacoti is a vector for Rickettsia akari, Coxiella burnetii, Francisella tularensis, Yersinia pestis, Eastern equine encephalitis virus (Alphavirus), Enterovirus (Picornaviridae), Langat virus (Flavivirus), and Hantaan orthohantavirus.^5,11-17 However, no cases of these infectious diseases being transmitted naturally have been reported.⁵

Confirmation of O bacoti as a vector for human pathogens is difficult because it relies on identification of the mite in the clinic.⁵ The epidemiologic importance of the mite in transmitting infectious disease is unknown; reports of human cases of mite infestation are rare. We present this information to increase awareness and help dermatologists and other health care providers identify O bacoti.

The tropical rat mite (Ornithonyssus bacoti) belongs to the family Macronyssidae. Theses mites are commonly mistaken for red bird mites or Nordic bird mites because they belong to the same family and have similar characteristics.¹ Although O bacoti is called the tropical rat mite, it also can be found in moderate climates.^2,3

Characteristics

The life cycle of a tropical rat mite lasts 11 to 13 days and includes 5 stages: egg, larva, protonymph, deutonymph, and adult.^1,2 The length of the mite (0.3–0.7 mm) varies with the stage of development.¹ Adults can reach 0.75 to 1.40 mm, with females larger than males and possibly visible with the naked eye.^1,2

Two or 3 days after a blood meal, the female mite lays approximately 100 eggs in its nest but not on the surface of a host. The eggs hatch into larvae after 1 to 4 days and go on to complete their life cyle.¹ During developmental stages, mites occupy their hosts for blood meals. Mites search for their hosts at night and prefer wild or pet rodents for blood meals but are not host specific and can be found on many mammals including birds, cats, racoons, and squirrels.⁴

Although tropical rat mites prefer rodent hosts, they can infest humans when their preferred host is unavailable. In the United States, the first case of human dermatitis due to a tropical rate mite occurred in 1923. In Europe, rat mite dermatitis was first reported in a human in 1931, possibly due to contamination of sailing vessels.⁴

Infestation and Transmission

Tropical rat mites prefer wild and pet rodents as hosts because the mites are able to feed on their blood over long periods.⁴ During the day, the mite spends most of its time hiding in dark dry spaces; it is most active during the night, traveling to find a host for meals.^3-5 If a preferred host is not present, the mite may choose to infest a human.⁵

Human infestation occurs most often upon close bodily contact with an infected animal or pet rodent that was sold without parasites having been eliminated.^3-5 Mites are able to survive without a host for as long as 6 months; they may travel after a meal.^1,2 Therefore, individuals who do not have a pet rodent can be infested if an infected wild rodent has infested their living space.^1,3-5

Clinical Presentation of Infestation

Patients infested with tropical rat mites present with pruritic cutaneous lesions, most often on unclothed parts of the body that are easily exposed to mites; lesions rarely occur on the scalp.⁵ People of any age or gender can be infested. Rat mite bites can present as single or grouped, pruritic, erythematous papules ranging in size from 4 to 10 mm in diameter.^5-7 Excoriations may be present due to excessive scratching. Although rare, vesicles or nodules have been reported.^5,7

Diagnosis of the underlying cause of the cutaneous manifestations often is difficult because mites are not visible during the day, as they are less active then.² Lesions often are misdiagnosed as an allergic response, a bacterial infection, or various forms of dermatitis.¹ A parasitic cause often is not considered unless the physician or patient detects a mite or many trials of therapies fail to provide relief.^1,3-5 Eliciting a thorough history may disclose that the patient has had close contact with rodents or lives in a community center, shelter, or shared space. If any of the patient’s close contacts have a similar presentation, infestation with mites should be considered.

Patients should be educated about treatment options and measures that need to be taken to prevent reinfection. It has been reported that tropical rat mites can survive without a blood meal for as long as 6 months; therefore, meticulous inspection and decontamination of all living spaces is required.^1,4 Once identified, physicians may prescribe an antiparasitic such as permethrin or pyriproxyfen to prevent further infestation and eliminate mites on the host.⁵ Lindane and benzyl benzoate previously were reported to be effective but should be prescribed only in correctly diagnosed cases due to the potential adverse effects of both therapies.^4,7-10 For effective treatment, physicians should thoroughly review the proper application of topical treatments with patients. Topical creams should be massaged into the skin from the head to the soles of the feet, covering all creases of the skin and between the fingers and toes. Antiparasitic creams should be left on the skin for 8 to 14 hours, and all members of the household should be examined and treated, if necessary, by a physician. A thorough bath removes tropical rat mites, but preventive measures should be taken to prevent reinfestation.⁴ Antihistamines or glucocorticoids also can be used as symptomatic treatment.^6,8

Avoiding Reinfestation—Preventive measures should be taken to prevent reinfestation, including evaluation by an exterminator for any wild rodents to remove nests and treat the living space with an acaricide.⁵ Insecticides administered by exterminators, including malathion, methyl carbamate, and lindane, also have been reported to be effective for preventing reinfestation.^5,7-9 A veterinarian should be consulted if the patient owns any pets to ensure proper identification of any potential tropical rat mites and treatments that may be necessary for any household pets.¹

Case Report

A 68-year-old man presented to the dermatology outpatient clinic with diffuse pruritus of the skin and scalp. He reported no other symptoms and had never had a total-body skin examination. His primary care physician recently prescribed a dose pack of methylprednisolone 4-mg tablets, which relieved the symptoms except for a mild scalp itch. His wife did not experience itching, and he denied noticing mites or fleas on his pet dog. Physical examination did not reveal any contributory findings, such as erythema or rash. Ketoconazole shampoo 2% and fluocinolone solution 0.01% were prescribed for scalp pruritus; however, he could not afford those medications and therefore did not take them.

Two weeks later, the patient presented with diffuse itching that involved the scalp, trunk, and extremities. He denied groin pruritus. He reported that the itching was worse at night. His wife continued to be asymptomatic. The patient reported that his health screening was up-to-date, and he had no interval health changes. A complete blood cell count, thyroid studies, and a comprehensive metabolic panel performed recently were within reference range. He denied recent travel or taking new medications. Physical examination revealed a somewhat linear distribution of erythematous urticarial papules on the right side of the abdomen. Red dermatographic excoriations were noted on the back. No burrows were visualized. He was given intramuscular triamcinolone 60 mg and was advised to have his house evaluated for bed bugs and his pet dog evaluated by a veterinarian for mites. During the triamcinolone injection, the medical assistant observed a 1- to 2-mm red insect, which fell into his clothing and could not be further evaluated.

After 1 month, the patient had no improvement of the pruritus; instead, it became worse. During this time, his wife developed intermittent urticarial-like eruptions. He was taking oral diphenhydramine nightly and applying triamcinolone cream 0.5% that he had at home from an earlier skin problem as needed. Physical examination findings correlated with worsening symptoms. He had multiple erythematous urticarial papules—many of which were excoriated—across the chest, abdomen, buttocks, and back. The arms had multiple excoriations. The urticarial papules coalesced in the anterior axillary folds, yet no burrows were visualized. In the left anterior axillary fold adjacent to one of the urticarial papules, a 1-mm mobile mite was identified on dermoscopy. Further evaluation by microscopy showed morphologic characteristics of a tropical rat mite (Figure). The patient admitted that his house had a mouse infestation that he was struggling to eliminate. Permethrin cream 5% was prescribed. Because the patient could not afford the prescription, he was advised to use the triamcinolone cream 0.5%and oral diphenhydramine that he had at home nightly for symptomatic relief. He was advised to hire an exterminator to eradicate the mouse and mite infestation to prevent reinfestation.

Yousif.jpg

Identification of Rate Mite Dermatitis

The characteristics of tropical rat mite dermatitis can be confused with many other conditions, such as infection. Even when a mite is identified, it can be difficult to classify it as a tropical rat mite. To confirm the diagnosis of tropical rat mite dermatitis, the parasite needs to be identified. Skin scrapings can be collected from pruritic lesions and examined microscopically in the hope of revealing the rat mites. The recommendation is to collect skin scrapings from the dorsal aspect of the hands or from the neck.⁵ Patients may report finding mites in their living space or on their bedding or clothing.

Although the tropical rat mite was reported as a vector for endemic typhus between humans, no other cases of transmission between humans have been reported since.^11,12 Studies reporting non–human subject research and case reports have shown that O bacoti is a vector for Rickettsia akari, Coxiella burnetii, Francisella tularensis, Yersinia pestis, Eastern equine encephalitis virus (Alphavirus), Enterovirus (Picornaviridae), Langat virus (Flavivirus), and Hantaan orthohantavirus.^5,11-17 However, no cases of these infectious diseases being transmitted naturally have been reported.⁵

Confirmation of O bacoti as a vector for human pathogens is difficult because it relies on identification of the mite in the clinic.⁵ The epidemiologic importance of the mite in transmitting infectious disease is unknown; reports of human cases of mite infestation are rare. We present this information to increase awareness and help dermatologists and other health care providers identify O bacoti.

Classification

Triatomine bugs (Triatoma) and the wheel bug (Arilus cristatus) are part of the family Reduviidae (order Hemiptera, a name that describes the sucking proboscis on the front of the insect’s head).^1,2 Both arthropods are found in multiple countries and are especially common in warmer areas, including in the United States, where they can be seen from Texas to California.^3,4 Because blood-feeding triatomines need a blood meal to survive while laying eggs and then throughout their 5 developmental nymph stages to undergo molting, they feed on mammals, such as opossums, raccoons, pack rats, and armadillos, whereas wheel bugs mainly prey on soft-bodied insects.^1,4-6

Triatoma bugs seek cutaneous blood vessels using thermosensors in their antennae to locate blood flow under the skin for feeding. After inserting the proboscis, they release nitric oxide and an anticoagulant that allows for continuous blood flow while feeding.⁷ It has been reported that triatomine bugs are not able to bite through clothing, instead seeking exposed skin, particularly near mucous membranes, such as the hands, arms, feet, head, and trunk. The name kissing bug for triatomines was coined because bites near the mouth are common.⁶ The bite typically is painless and occurs mainly at night when the insect is most active. After obtaining a blood meal, triatomine bugs seek shelter and hide in mud and daub structures, cracks, crevices, and furniture.^1,8

Unlike Triatoma species, A cristatus does not require a blood meal for development and survival, leading it to prey on soft-bodied insects. Piercing prey with the proboscis, wheel bugs inject a toxin to digest the contents and suck the digested contents through this apparatus.⁴ Because the wheel bug does not require a blood meal, it typically bites a human only for defense if it feels threatened. Unlike the painless bite of a triatomine bug, the bite of A cristatus is extremely painful; it has been described as the worst arthropod bite—worse than a hornet’s sting. The pain from the bite is caused by the toxin being injected into the skin; possible retention of the proboscis makes the pain worse.^4,9 In addition, when A cristatus is disturbed, it exudes pungent material from a pair of bright orange subrectal glands while stridulating to repulse predators.⁹

Although Triatoma species and A cristatus have separate roles in nature and vastly different impacts on health, they often are mistaken for the same arthropod when seen in nature. Features that members of Reduviidae share include large bodies (relative to their overall length); long thin legs; a narrow head; wings; and a long sucking proboscis on the front of the head.¹⁰

Boswell_1.jpg

Characteristics that differentiate Triatoma and A cristatus species include size, color, and distinctive markings. Most triatomine bugs are 12- to 36-mm long; are dark brown or black; and have what are called tiger-stripe orange markings on the peripheral two-thirds of the body (Figure 1).¹¹ In contrast, wheel bugs commonly are bigger—measuring longer than 1.25 inches—and gray, with a cogwheel-like structure on the thorax (Figure 2).¹⁰

Boswell_2.jpg

Dermatologic Presentation and Clinical Symptoms

The area of involved skin on patients presenting with Triatoma or A cristatus bites may resemble other insect bites. Many bites from Triatoma bugs and A cristatus initially present as an erythematous, raised, pruritic papule with a central punctum that is visible because of the involvement of the proboscis. However, other presentations of bites from both arthropods have been reported^4,6,7: grouped vesicles on an erythematous base; indurated, giant, urticarial-type wheels measuring 10 to 15 mm in diameter; and hemorrhagic bullous nodules (Figure 3). Associated lymphangitis or lymphadenitis is typical of the latter 2 variations.⁶ These variations in presentation can be mistaken for other causes of similarly presenting lesions, such as shingles or spider bites, leading to delayed or missed diagnosis.

Boswell_3.jpg

Patients may present with a single bite or multiple bites due to the feeding pattern of Triatoma bugs; if the host moves or disrupts its feeding, the arthropod takes multiple bites to finish feeding.⁸ In comparison, 4 common variations of wheel bug bites have been reported: (1) a painful bite without complications; (2) a cutaneous horn and papilloma at the site of toxin injection; (3) a necrotic ulcer around the central punctum caused by injected toxin; and (4) an abscess under the central punctum due to secondary infection.⁴

Anaphylaxis—Although the bites of Triatoma and A cristatus present differently, both can cause anaphylaxis. Triatoma is implicated more often than A cristatus as the cause of anaphylaxis.¹² In fact, Triatoma bites are among the more common causes of anaphylaxis from bug bites, with multiple cases of these reactions reported in the literature.^12,13

Symptoms of Triatoma anaphylaxis include acute-onset urticarial rash, flushing, dyspnea, wheezing, nausea, vomiting, and localized edema.² The cause of anaphylaxis is proteins in Triatoma saliva, including 20-kDa procalin, which incites the systemic reaction. Other potential causes of anaphylaxis include serine protease, which has similarities to salivary protein and desmoglein in humans.¹¹

The degree of reaction to a bite depends on the patient's sensitization to antigenic proteins in each insect’s saliva.^4,6 Patients who have a bite from a triatomine bug are at risk for subsequent bites, as household infestation is likely due to the pliability of the insect, allowing it to hide in small spaces unnoticed.⁸ In the case of a bite from Triatoma or A cristatus, sensitization may lead to severe and worsening reactions with subsequent bites, which ultimately can result in life-threatening anaphylaxis.^1,6

Treatment and Prevention

Treatment of Triatoma and A cristatus bites depends on the severity of the patient’s reaction to the bite. A local reaction to a bite from either insect can be treated supportively with local corticosteroids and antihistamines.³ If the patient is sensitized to proteins associated with a bite, standard anaphylaxis treatment such as epinephrine and intravenous antihistamines may be indicated.¹⁴ Secondary infection can be treated with antibiotics; a formed abscess might need to be drained or debrided.¹⁵

There’s No Place Like Home—Because Triatoma bugs have a pliable exoskeleton and can squeeze into small spaces, they commonly infest dwellings where they find multiple attractants: light, heat, carbon dioxide, and lactic acid.⁸ The more household occupants (including pets), the higher the levels of carbon dioxide and lactic acid, thus the greater the attraction. Infestation of a home can lead to the spread of diseases harbored by Triatoma, including Chagas disease, which is caused by the parasite Trypanosoma cruzi.⁵

Preventive measures can be taken to reduce the risk and extent of home infestation by Triatoma bugs, including insecticides, a solid foundation, window screens, air conditioning, sealing of cracks and crevices, outdoor light management, and removal of clutter throughout the house.⁸ Because Triatoma bugs cannot bite through clothing, protective clothing and bug repellent on exposed skin can be employed. Another degree of protection is offered by pest management, especially control of rodents by removing food, water, and nests in areas where triatomine bugs feed off of that population.^8,14

Unlike triatomine bugs, wheel bugs tend not to invade houses; therefore, these preventive measures are unnecessary. If a wheel bug is identified, do not engage the arthropod due to the defensive nature of its attack.^4,9 Such deliberate avoidance should ensure protection from the wheel bug’s painful bite.

Medical Complications

Although triatomine bugs and wheel bugs are in the same taxonomic family, subsequent infection is unique to Triatoma bugs because they need a blood meal to survive. Because Triatoma bugs feed on mammals, they present an increased opportunity for transmitting the causative agents of infection from hosts on which they have fed.¹² The principal parasite transmitted by triatomines is T cruzi, which causes Chagas disease and lives in the gastrointestinal (GI) tract of the insect.⁵ When a triatomine bug seeks out a mucosal surface to bite, including the mouth, it defecates and urinates during or shortly after feeding, leading to contamination of the initial wound or mucosal surfaces. In addition, Triatoma bugs are vectors for transmission of Serratia marcescans, Bartonella henselae, and Mycobacterium leprae.¹⁶

Chagas Disease—This infection has 3 stages: acute, intermediate, and chronic.⁵ The acute stage can present with symptoms of conjunctivitis, fever, lymphadenopathy, hepatosplenomegaly, and anemia. The intermediate stage typically is asymptomatic. The chronic stage usually involves the heart and GI tract and causes cardiac aneurysms, cardiomegaly, megacolon, and megaesophagus. Initial symptoms can be a localized nodule (chagoma) at the inoculation site, fever, fatigue, lymphadenopathy, and hepatosplenomegaly.² Unilateral palpebral edema with associated lymphadenopathy (Romaña sign) also can be seen—not to be confused with bilateral swelling in an acute reaction to an insect bite. Romaña sign is pathognomonic of T cruzi infection; bilateral palpebral swelling is typical of an allergic reaction.¹²

Identification of a triatomine bite is the first step in diagnosing Chagas disease, which can be life-threatening. Among chronic carriers of Chagas disease, 30% develop GI and cardiac symptoms, of which 20% to 30% develop cardiomyopathy, with serious symptoms that present 10 to 20 years after the asymptomatic intermediate phase.²

Chagas disease is endemic to Central and South America but is also seen in North America; 28,000 new cases are reported annually in South America and North America combined. Human migration from endemic areas and from rural to urban areas has promoted the spread of Chagas disease.² However, patients in the United States have a relatively low risk for Chagas disease, largely because of the quality of housing construction and use of insecticides.

Treatment options for Chagas disease include nifurtimox and benznidazole. Without treatment, the host immune response typically controls acute replication of the parasite but will lead to a chronic state, ultimately involving the heart and GI tract.⁵

Classification

Triatomine bugs (Triatoma) and the wheel bug (Arilus cristatus) are part of the family Reduviidae (order Hemiptera, a name that describes the sucking proboscis on the front of the insect’s head).^1,2 Both arthropods are found in multiple countries and are especially common in warmer areas, including in the United States, where they can be seen from Texas to California.^3,4 Because blood-feeding triatomines need a blood meal to survive while laying eggs and then throughout their 5 developmental nymph stages to undergo molting, they feed on mammals, such as opossums, raccoons, pack rats, and armadillos, whereas wheel bugs mainly prey on soft-bodied insects.^1,4-6

Triatoma bugs seek cutaneous blood vessels using thermosensors in their antennae to locate blood flow under the skin for feeding. After inserting the proboscis, they release nitric oxide and an anticoagulant that allows for continuous blood flow while feeding.⁷ It has been reported that triatomine bugs are not able to bite through clothing, instead seeking exposed skin, particularly near mucous membranes, such as the hands, arms, feet, head, and trunk. The name kissing bug for triatomines was coined because bites near the mouth are common.⁶ The bite typically is painless and occurs mainly at night when the insect is most active. After obtaining a blood meal, triatomine bugs seek shelter and hide in mud and daub structures, cracks, crevices, and furniture.^1,8

Unlike Triatoma species, A cristatus does not require a blood meal for development and survival, leading it to prey on soft-bodied insects. Piercing prey with the proboscis, wheel bugs inject a toxin to digest the contents and suck the digested contents through this apparatus.⁴ Because the wheel bug does not require a blood meal, it typically bites a human only for defense if it feels threatened. Unlike the painless bite of a triatomine bug, the bite of A cristatus is extremely painful; it has been described as the worst arthropod bite—worse than a hornet’s sting. The pain from the bite is caused by the toxin being injected into the skin; possible retention of the proboscis makes the pain worse.^4,9 In addition, when A cristatus is disturbed, it exudes pungent material from a pair of bright orange subrectal glands while stridulating to repulse predators.⁹

Although Triatoma species and A cristatus have separate roles in nature and vastly different impacts on health, they often are mistaken for the same arthropod when seen in nature. Features that members of Reduviidae share include large bodies (relative to their overall length); long thin legs; a narrow head; wings; and a long sucking proboscis on the front of the head.¹⁰

Boswell_1.jpg

Characteristics that differentiate Triatoma and A cristatus species include size, color, and distinctive markings. Most triatomine bugs are 12- to 36-mm long; are dark brown or black; and have what are called tiger-stripe orange markings on the peripheral two-thirds of the body (Figure 1).¹¹ In contrast, wheel bugs commonly are bigger—measuring longer than 1.25 inches—and gray, with a cogwheel-like structure on the thorax (Figure 2).¹⁰

Boswell_2.jpg

Dermatologic Presentation and Clinical Symptoms

The area of involved skin on patients presenting with Triatoma or A cristatus bites may resemble other insect bites. Many bites from Triatoma bugs and A cristatus initially present as an erythematous, raised, pruritic papule with a central punctum that is visible because of the involvement of the proboscis. However, other presentations of bites from both arthropods have been reported^4,6,7: grouped vesicles on an erythematous base; indurated, giant, urticarial-type wheels measuring 10 to 15 mm in diameter; and hemorrhagic bullous nodules (Figure 3). Associated lymphangitis or lymphadenitis is typical of the latter 2 variations.⁶ These variations in presentation can be mistaken for other causes of similarly presenting lesions, such as shingles or spider bites, leading to delayed or missed diagnosis.

Boswell_3.jpg

Patients may present with a single bite or multiple bites due to the feeding pattern of Triatoma bugs; if the host moves or disrupts its feeding, the arthropod takes multiple bites to finish feeding.⁸ In comparison, 4 common variations of wheel bug bites have been reported: (1) a painful bite without complications; (2) a cutaneous horn and papilloma at the site of toxin injection; (3) a necrotic ulcer around the central punctum caused by injected toxin; and (4) an abscess under the central punctum due to secondary infection.⁴

Anaphylaxis—Although the bites of Triatoma and A cristatus present differently, both can cause anaphylaxis. Triatoma is implicated more often than A cristatus as the cause of anaphylaxis.¹² In fact, Triatoma bites are among the more common causes of anaphylaxis from bug bites, with multiple cases of these reactions reported in the literature.^12,13

Symptoms of Triatoma anaphylaxis include acute-onset urticarial rash, flushing, dyspnea, wheezing, nausea, vomiting, and localized edema.² The cause of anaphylaxis is proteins in Triatoma saliva, including 20-kDa procalin, which incites the systemic reaction. Other potential causes of anaphylaxis include serine protease, which has similarities to salivary protein and desmoglein in humans.¹¹

The degree of reaction to a bite depends on the patient's sensitization to antigenic proteins in each insect’s saliva.^4,6 Patients who have a bite from a triatomine bug are at risk for subsequent bites, as household infestation is likely due to the pliability of the insect, allowing it to hide in small spaces unnoticed.⁸ In the case of a bite from Triatoma or A cristatus, sensitization may lead to severe and worsening reactions with subsequent bites, which ultimately can result in life-threatening anaphylaxis.^1,6

Treatment and Prevention

Treatment of Triatoma and A cristatus bites depends on the severity of the patient’s reaction to the bite. A local reaction to a bite from either insect can be treated supportively with local corticosteroids and antihistamines.³ If the patient is sensitized to proteins associated with a bite, standard anaphylaxis treatment such as epinephrine and intravenous antihistamines may be indicated.¹⁴ Secondary infection can be treated with antibiotics; a formed abscess might need to be drained or debrided.¹⁵

There’s No Place Like Home—Because Triatoma bugs have a pliable exoskeleton and can squeeze into small spaces, they commonly infest dwellings where they find multiple attractants: light, heat, carbon dioxide, and lactic acid.⁸ The more household occupants (including pets), the higher the levels of carbon dioxide and lactic acid, thus the greater the attraction. Infestation of a home can lead to the spread of diseases harbored by Triatoma, including Chagas disease, which is caused by the parasite Trypanosoma cruzi.⁵

Preventive measures can be taken to reduce the risk and extent of home infestation by Triatoma bugs, including insecticides, a solid foundation, window screens, air conditioning, sealing of cracks and crevices, outdoor light management, and removal of clutter throughout the house.⁸ Because Triatoma bugs cannot bite through clothing, protective clothing and bug repellent on exposed skin can be employed. Another degree of protection is offered by pest management, especially control of rodents by removing food, water, and nests in areas where triatomine bugs feed off of that population.^8,14

Unlike triatomine bugs, wheel bugs tend not to invade houses; therefore, these preventive measures are unnecessary. If a wheel bug is identified, do not engage the arthropod due to the defensive nature of its attack.^4,9 Such deliberate avoidance should ensure protection from the wheel bug’s painful bite.

Medical Complications

Although triatomine bugs and wheel bugs are in the same taxonomic family, subsequent infection is unique to Triatoma bugs because they need a blood meal to survive. Because Triatoma bugs feed on mammals, they present an increased opportunity for transmitting the causative agents of infection from hosts on which they have fed.¹² The principal parasite transmitted by triatomines is T cruzi, which causes Chagas disease and lives in the gastrointestinal (GI) tract of the insect.⁵ When a triatomine bug seeks out a mucosal surface to bite, including the mouth, it defecates and urinates during or shortly after feeding, leading to contamination of the initial wound or mucosal surfaces. In addition, Triatoma bugs are vectors for transmission of Serratia marcescans, Bartonella henselae, and Mycobacterium leprae.¹⁶

Chagas Disease—This infection has 3 stages: acute, intermediate, and chronic.⁵ The acute stage can present with symptoms of conjunctivitis, fever, lymphadenopathy, hepatosplenomegaly, and anemia. The intermediate stage typically is asymptomatic. The chronic stage usually involves the heart and GI tract and causes cardiac aneurysms, cardiomegaly, megacolon, and megaesophagus. Initial symptoms can be a localized nodule (chagoma) at the inoculation site, fever, fatigue, lymphadenopathy, and hepatosplenomegaly.² Unilateral palpebral edema with associated lymphadenopathy (Romaña sign) also can be seen—not to be confused with bilateral swelling in an acute reaction to an insect bite. Romaña sign is pathognomonic of T cruzi infection; bilateral palpebral swelling is typical of an allergic reaction.¹²

Identification of a triatomine bite is the first step in diagnosing Chagas disease, which can be life-threatening. Among chronic carriers of Chagas disease, 30% develop GI and cardiac symptoms, of which 20% to 30% develop cardiomyopathy, with serious symptoms that present 10 to 20 years after the asymptomatic intermediate phase.²

Chagas disease is endemic to Central and South America but is also seen in North America; 28,000 new cases are reported annually in South America and North America combined. Human migration from endemic areas and from rural to urban areas has promoted the spread of Chagas disease.² However, patients in the United States have a relatively low risk for Chagas disease, largely because of the quality of housing construction and use of insecticides.

Treatment options for Chagas disease include nifurtimox and benznidazole. Without treatment, the host immune response typically controls acute replication of the parasite but will lead to a chronic state, ultimately involving the heart and GI tract.⁵

Classification

Triatomine bugs (Triatoma) and the wheel bug (Arilus cristatus) are part of the family Reduviidae (order Hemiptera, a name that describes the sucking proboscis on the front of the insect’s head).^1,2 Both arthropods are found in multiple countries and are especially common in warmer areas, including in the United States, where they can be seen from Texas to California.^3,4 Because blood-feeding triatomines need a blood meal to survive while laying eggs and then throughout their 5 developmental nymph stages to undergo molting, they feed on mammals, such as opossums, raccoons, pack rats, and armadillos, whereas wheel bugs mainly prey on soft-bodied insects.^1,4-6

Triatoma bugs seek cutaneous blood vessels using thermosensors in their antennae to locate blood flow under the skin for feeding. After inserting the proboscis, they release nitric oxide and an anticoagulant that allows for continuous blood flow while feeding.⁷ It has been reported that triatomine bugs are not able to bite through clothing, instead seeking exposed skin, particularly near mucous membranes, such as the hands, arms, feet, head, and trunk. The name kissing bug for triatomines was coined because bites near the mouth are common.⁶ The bite typically is painless and occurs mainly at night when the insect is most active. After obtaining a blood meal, triatomine bugs seek shelter and hide in mud and daub structures, cracks, crevices, and furniture.^1,8

Unlike Triatoma species, A cristatus does not require a blood meal for development and survival, leading it to prey on soft-bodied insects. Piercing prey with the proboscis, wheel bugs inject a toxin to digest the contents and suck the digested contents through this apparatus.⁴ Because the wheel bug does not require a blood meal, it typically bites a human only for defense if it feels threatened. Unlike the painless bite of a triatomine bug, the bite of A cristatus is extremely painful; it has been described as the worst arthropod bite—worse than a hornet’s sting. The pain from the bite is caused by the toxin being injected into the skin; possible retention of the proboscis makes the pain worse.^4,9 In addition, when A cristatus is disturbed, it exudes pungent material from a pair of bright orange subrectal glands while stridulating to repulse predators.⁹

Although Triatoma species and A cristatus have separate roles in nature and vastly different impacts on health, they often are mistaken for the same arthropod when seen in nature. Features that members of Reduviidae share include large bodies (relative to their overall length); long thin legs; a narrow head; wings; and a long sucking proboscis on the front of the head.¹⁰

Boswell_1.jpg

Characteristics that differentiate Triatoma and A cristatus species include size, color, and distinctive markings. Most triatomine bugs are 12- to 36-mm long; are dark brown or black; and have what are called tiger-stripe orange markings on the peripheral two-thirds of the body (Figure 1).¹¹ In contrast, wheel bugs commonly are bigger—measuring longer than 1.25 inches—and gray, with a cogwheel-like structure on the thorax (Figure 2).¹⁰

Boswell_2.jpg

Dermatologic Presentation and Clinical Symptoms

The area of involved skin on patients presenting with Triatoma or A cristatus bites may resemble other insect bites. Many bites from Triatoma bugs and A cristatus initially present as an erythematous, raised, pruritic papule with a central punctum that is visible because of the involvement of the proboscis. However, other presentations of bites from both arthropods have been reported^4,6,7: grouped vesicles on an erythematous base; indurated, giant, urticarial-type wheels measuring 10 to 15 mm in diameter; and hemorrhagic bullous nodules (Figure 3). Associated lymphangitis or lymphadenitis is typical of the latter 2 variations.⁶ These variations in presentation can be mistaken for other causes of similarly presenting lesions, such as shingles or spider bites, leading to delayed or missed diagnosis.

Boswell_3.jpg

Patients may present with a single bite or multiple bites due to the feeding pattern of Triatoma bugs; if the host moves or disrupts its feeding, the arthropod takes multiple bites to finish feeding.⁸ In comparison, 4 common variations of wheel bug bites have been reported: (1) a painful bite without complications; (2) a cutaneous horn and papilloma at the site of toxin injection; (3) a necrotic ulcer around the central punctum caused by injected toxin; and (4) an abscess under the central punctum due to secondary infection.⁴

Anaphylaxis—Although the bites of Triatoma and A cristatus present differently, both can cause anaphylaxis. Triatoma is implicated more often than A cristatus as the cause of anaphylaxis.¹² In fact, Triatoma bites are among the more common causes of anaphylaxis from bug bites, with multiple cases of these reactions reported in the literature.^12,13

Symptoms of Triatoma anaphylaxis include acute-onset urticarial rash, flushing, dyspnea, wheezing, nausea, vomiting, and localized edema.² The cause of anaphylaxis is proteins in Triatoma saliva, including 20-kDa procalin, which incites the systemic reaction. Other potential causes of anaphylaxis include serine protease, which has similarities to salivary protein and desmoglein in humans.¹¹

The degree of reaction to a bite depends on the patient's sensitization to antigenic proteins in each insect’s saliva.^4,6 Patients who have a bite from a triatomine bug are at risk for subsequent bites, as household infestation is likely due to the pliability of the insect, allowing it to hide in small spaces unnoticed.⁸ In the case of a bite from Triatoma or A cristatus, sensitization may lead to severe and worsening reactions with subsequent bites, which ultimately can result in life-threatening anaphylaxis.^1,6

Treatment and Prevention

Treatment of Triatoma and A cristatus bites depends on the severity of the patient’s reaction to the bite. A local reaction to a bite from either insect can be treated supportively with local corticosteroids and antihistamines.³ If the patient is sensitized to proteins associated with a bite, standard anaphylaxis treatment such as epinephrine and intravenous antihistamines may be indicated.¹⁴ Secondary infection can be treated with antibiotics; a formed abscess might need to be drained or debrided.¹⁵

There’s No Place Like Home—Because Triatoma bugs have a pliable exoskeleton and can squeeze into small spaces, they commonly infest dwellings where they find multiple attractants: light, heat, carbon dioxide, and lactic acid.⁸ The more household occupants (including pets), the higher the levels of carbon dioxide and lactic acid, thus the greater the attraction. Infestation of a home can lead to the spread of diseases harbored by Triatoma, including Chagas disease, which is caused by the parasite Trypanosoma cruzi.⁵

Preventive measures can be taken to reduce the risk and extent of home infestation by Triatoma bugs, including insecticides, a solid foundation, window screens, air conditioning, sealing of cracks and crevices, outdoor light management, and removal of clutter throughout the house.⁸ Because Triatoma bugs cannot bite through clothing, protective clothing and bug repellent on exposed skin can be employed. Another degree of protection is offered by pest management, especially control of rodents by removing food, water, and nests in areas where triatomine bugs feed off of that population.^8,14

Unlike triatomine bugs, wheel bugs tend not to invade houses; therefore, these preventive measures are unnecessary. If a wheel bug is identified, do not engage the arthropod due to the defensive nature of its attack.^4,9 Such deliberate avoidance should ensure protection from the wheel bug’s painful bite.

Medical Complications

Although triatomine bugs and wheel bugs are in the same taxonomic family, subsequent infection is unique to Triatoma bugs because they need a blood meal to survive. Because Triatoma bugs feed on mammals, they present an increased opportunity for transmitting the causative agents of infection from hosts on which they have fed.¹² The principal parasite transmitted by triatomines is T cruzi, which causes Chagas disease and lives in the gastrointestinal (GI) tract of the insect.⁵ When a triatomine bug seeks out a mucosal surface to bite, including the mouth, it defecates and urinates during or shortly after feeding, leading to contamination of the initial wound or mucosal surfaces. In addition, Triatoma bugs are vectors for transmission of Serratia marcescans, Bartonella henselae, and Mycobacterium leprae.¹⁶

Chagas Disease—This infection has 3 stages: acute, intermediate, and chronic.⁵ The acute stage can present with symptoms of conjunctivitis, fever, lymphadenopathy, hepatosplenomegaly, and anemia. The intermediate stage typically is asymptomatic. The chronic stage usually involves the heart and GI tract and causes cardiac aneurysms, cardiomegaly, megacolon, and megaesophagus. Initial symptoms can be a localized nodule (chagoma) at the inoculation site, fever, fatigue, lymphadenopathy, and hepatosplenomegaly.² Unilateral palpebral edema with associated lymphadenopathy (Romaña sign) also can be seen—not to be confused with bilateral swelling in an acute reaction to an insect bite. Romaña sign is pathognomonic of T cruzi infection; bilateral palpebral swelling is typical of an allergic reaction.¹²

Identification of a triatomine bite is the first step in diagnosing Chagas disease, which can be life-threatening. Among chronic carriers of Chagas disease, 30% develop GI and cardiac symptoms, of which 20% to 30% develop cardiomyopathy, with serious symptoms that present 10 to 20 years after the asymptomatic intermediate phase.²

Chagas disease is endemic to Central and South America but is also seen in North America; 28,000 new cases are reported annually in South America and North America combined. Human migration from endemic areas and from rural to urban areas has promoted the spread of Chagas disease.² However, patients in the United States have a relatively low risk for Chagas disease, largely because of the quality of housing construction and use of insecticides.

Treatment options for Chagas disease include nifurtimox and benznidazole. Without treatment, the host immune response typically controls acute replication of the parasite but will lead to a chronic state, ultimately involving the heart and GI tract.⁵

Cutaneous Manifestations

Capsicum peppers are used worldwide in preparing spicy dishes. Their active ingredient—capsaicin—is used as a topical medicine to treat localized pain. Capsicum peppers can cause irritant contact dermatitis with symptoms of erythema, cutaneous burning, and itch.¹

Irritant contact dermatitis is a common occupational skin disorder. Many cooks have experienced the sting of a chili pepper after contact with the hands or eyes. Cases of chronic exposure to Capsicum peppers with persistent burning and pain have been called Hunan hand syndrome.²Capsicum peppers also have induced allergic contact dermatitis in a food production worker.³

Capsicum peppers also are used in pepper spray, tear gas, and animal repellents because of their stinging properties. These agents usually cause cutaneous tingling and burning that soon resolves; however, a review of 31 studies showed that crowd-control methods with Capsicum-containing tear gas and pepper spray can cause moderate to severe skin damage such as a persistent skin rash or erythema, or even first-, second-, or third-degree burns.⁴

Topical application of capsaicin isolate is meant to cause burning and deplete local neuropeptides, with a cutaneous reaction that ranges from mild to intolerable.^5,6 Capsaicin also is found in other products. In one published case report, a 3-year-old boy broke out in facial urticaria when his mother kissed him on the cheek after she applied lip plumper containing capsaicin to her lips.⁷ Dermatologists should consider capsaicin an active ingredient that can irritate the skin in the garden, in the kitchen, and in topical products.

Obtaining Relief

Capsaicin-induced dermatitis can be relieved by washing the area with soap, detergent, baking soda, or oily compounds that act as solvents for the nonpolar capsaicin.⁸ Application of ice water or a high-potency topical steroid also may help. If the reaction is severe and persistent, a continuous stellate ganglion block may alleviate the pain of capsaicin-induced contact dermatitis.⁹

Identifying Features and Plant Facts

The Capsicum genus includes chili peppers, paprika, and red peppers. Capsicum peppers are native to tropical regions of the Americas (Figure). The use of Capsicum peppers in food can be traced to Indigenous peoples of Mexico as early as 7000 bc.¹⁰ On the Scoville scale, which was developed to quantify the hotness of foods and spices, Capsicum peppers are rated at approximately 2 million units; by comparison, jalapeño peppers have a Scoville score of 4500¹¹ and capsaicin isolate has a score of 16 million units. Capsicum species rank among the hottest peppers in the world.

Barker_Botanical.jpg

Capsicum belongs to the family Solanaceae, which includes tobacco, tomatoes, potatoes, and nightshade plants. There are many varieties of peppers in the Capsicum genus, with 5 domesticated species: Capsicum annuum, Capsicum baccatum, Capsicum chinense, Capsicum frutescens, and Capsicum pubescens. These include bell, poblano, cayenne, tabasco, habanero, and ají peppers, among others. Capsicum species grow as a shrub with flowers that rotate to stellate corollas and rounded berries of different sizes and colors.¹² Capsaicin and other alkaloids are concentrated in the fruit; therefore, Capsicum dermatitis is most commonly induced by contact with the flesh of peppers.

Capsaicin (8-methyl-6-nonanoyl vanillylamide) is a nonpolar phenol, which is why washing skin that has come in contact with capsaicin with water or vinegar alone is insufficient to solubilize it.¹³ Capsaicin binds to the transient receptor potential vanilloid 1 (TRPV1), a calcium channel on neurons that opens in response to heat. When bound, the channel opens at a lower temperature threshold and depolarizes nerve endings, leading to vasodilation and activation of sensory nerves.¹⁴ Substance P is released and the individual experiences a painful burning sensation. When purified capsaicin is frequently applied at an appropriate dose, synthesis of substance P is diminished, resulting in reduced local pain overall.¹⁵

Capsaicin does not affect neurons without TRPV1, and administration of capsaicin is not painful if given with anesthesia. An inappropriately high dose of capsaicin destroys cells in the epidermal barrier, resulting in water loss and inducing release of vasoactive peptides and inflammatory cytokines.¹ Careful handling of Capsicum peppers and capsaicin products can reduce the risk for irritation.

Medicinal Use

On-/Off-Label and Potential Uses—Capsaicin is US Food and Drug Administration approved for use in arthritis and musculoskeletal pain. It also is used to treat diabetic neuropathy,⁵ postherpetic neuralgia,⁶ psoriasis,¹⁶ and other conditions. Studies have shown that capsaicin might be useful in treating trigeminal neuralgia,¹⁷ fibromyalgia,¹⁸ migraines,¹⁴ cluster headaches,⁹ and HIV-associated distal sensory neuropathy.⁵

Delivery of Capsaicin—Capsaicin preferentially acts on C-fibers, which transmit dull, aching, chronic pain.¹⁹ The compound is available as a cream, lotion, and large bandage (for the lower back), as well as low- and high-dose patches. Capsaicin creams, lotions, and the low-dose patch are uncomfortable and must be applied for 4 to 6 weeks to take effect, which may impact patient adherence. The high-dose patch, which requires administration under local anesthesia by a health care worker, brings pain relief with a single use and improves adherence.¹¹ Synthetic TRPV1-agonist injectables based on capsaicin have undergone clinical trials for localized pain (eg, postoperative musculoskeletal pain); many patients experience pain relief, though benefit fades over weeks to months.^20,21

Use in Traditional Medicine—Capsicum peppers have been used to aid digestion and promote healing in gastrointestinal conditions, such as dyspepsia.²² The peppers are a source of important vitamins and minerals, including vitamins A, C, and E; many of the B complex vitamins; and magnesium, calcium, and iron.²³

Use as Cancer Therapy—Studies of the use of capsaicin in treating cancer have produced controversial results. In cell and animal models, capsaicin induces apoptosis through downregulation of the Bcl-2 protein; upregulation of oxidative stress, tribbles-related protein 3 (TRIB3), and caspase-3; and other pathways.^19,24-26 On the other hand, consumption of Capsicum peppers has been associated with cancer of the stomach and gallbladder.²⁷ Capsaicin might have anticarcinogenic properties, but its mechanism of action varies, depending on variables not fully understood.

Final Thoughts

Capsaicin is a neuropeptide-active compound found in Capsicum peppers that has many promising applications for use. However, dermatologists should be aware of the possibility of a skin reaction to this compound from handling peppers and using topical medicines. Exposure to capsaicin can cause irritant contact dermatitis that may require clinical care.

Cutaneous Manifestations

Capsicum peppers are used worldwide in preparing spicy dishes. Their active ingredient—capsaicin—is used as a topical medicine to treat localized pain. Capsicum peppers can cause irritant contact dermatitis with symptoms of erythema, cutaneous burning, and itch.¹

Irritant contact dermatitis is a common occupational skin disorder. Many cooks have experienced the sting of a chili pepper after contact with the hands or eyes. Cases of chronic exposure to Capsicum peppers with persistent burning and pain have been called Hunan hand syndrome.²Capsicum peppers also have induced allergic contact dermatitis in a food production worker.³

Capsicum peppers also are used in pepper spray, tear gas, and animal repellents because of their stinging properties. These agents usually cause cutaneous tingling and burning that soon resolves; however, a review of 31 studies showed that crowd-control methods with Capsicum-containing tear gas and pepper spray can cause moderate to severe skin damage such as a persistent skin rash or erythema, or even first-, second-, or third-degree burns.⁴

Topical application of capsaicin isolate is meant to cause burning and deplete local neuropeptides, with a cutaneous reaction that ranges from mild to intolerable.^5,6 Capsaicin also is found in other products. In one published case report, a 3-year-old boy broke out in facial urticaria when his mother kissed him on the cheek after she applied lip plumper containing capsaicin to her lips.⁷ Dermatologists should consider capsaicin an active ingredient that can irritate the skin in the garden, in the kitchen, and in topical products.

Obtaining Relief

Capsaicin-induced dermatitis can be relieved by washing the area with soap, detergent, baking soda, or oily compounds that act as solvents for the nonpolar capsaicin.⁸ Application of ice water or a high-potency topical steroid also may help. If the reaction is severe and persistent, a continuous stellate ganglion block may alleviate the pain of capsaicin-induced contact dermatitis.⁹

Identifying Features and Plant Facts

The Capsicum genus includes chili peppers, paprika, and red peppers. Capsicum peppers are native to tropical regions of the Americas (Figure). The use of Capsicum peppers in food can be traced to Indigenous peoples of Mexico as early as 7000 bc.¹⁰ On the Scoville scale, which was developed to quantify the hotness of foods and spices, Capsicum peppers are rated at approximately 2 million units; by comparison, jalapeño peppers have a Scoville score of 4500¹¹ and capsaicin isolate has a score of 16 million units. Capsicum species rank among the hottest peppers in the world.

Barker_Botanical.jpg

Capsicum belongs to the family Solanaceae, which includes tobacco, tomatoes, potatoes, and nightshade plants. There are many varieties of peppers in the Capsicum genus, with 5 domesticated species: Capsicum annuum, Capsicum baccatum, Capsicum chinense, Capsicum frutescens, and Capsicum pubescens. These include bell, poblano, cayenne, tabasco, habanero, and ají peppers, among others. Capsicum species grow as a shrub with flowers that rotate to stellate corollas and rounded berries of different sizes and colors.¹² Capsaicin and other alkaloids are concentrated in the fruit; therefore, Capsicum dermatitis is most commonly induced by contact with the flesh of peppers.

Capsaicin (8-methyl-6-nonanoyl vanillylamide) is a nonpolar phenol, which is why washing skin that has come in contact with capsaicin with water or vinegar alone is insufficient to solubilize it.¹³ Capsaicin binds to the transient receptor potential vanilloid 1 (TRPV1), a calcium channel on neurons that opens in response to heat. When bound, the channel opens at a lower temperature threshold and depolarizes nerve endings, leading to vasodilation and activation of sensory nerves.¹⁴ Substance P is released and the individual experiences a painful burning sensation. When purified capsaicin is frequently applied at an appropriate dose, synthesis of substance P is diminished, resulting in reduced local pain overall.¹⁵

Capsaicin does not affect neurons without TRPV1, and administration of capsaicin is not painful if given with anesthesia. An inappropriately high dose of capsaicin destroys cells in the epidermal barrier, resulting in water loss and inducing release of vasoactive peptides and inflammatory cytokines.¹ Careful handling of Capsicum peppers and capsaicin products can reduce the risk for irritation.

Medicinal Use

On-/Off-Label and Potential Uses—Capsaicin is US Food and Drug Administration approved for use in arthritis and musculoskeletal pain. It also is used to treat diabetic neuropathy,⁵ postherpetic neuralgia,⁶ psoriasis,¹⁶ and other conditions. Studies have shown that capsaicin might be useful in treating trigeminal neuralgia,¹⁷ fibromyalgia,¹⁸ migraines,¹⁴ cluster headaches,⁹ and HIV-associated distal sensory neuropathy.⁵

Delivery of Capsaicin—Capsaicin preferentially acts on C-fibers, which transmit dull, aching, chronic pain.¹⁹ The compound is available as a cream, lotion, and large bandage (for the lower back), as well as low- and high-dose patches. Capsaicin creams, lotions, and the low-dose patch are uncomfortable and must be applied for 4 to 6 weeks to take effect, which may impact patient adherence. The high-dose patch, which requires administration under local anesthesia by a health care worker, brings pain relief with a single use and improves adherence.¹¹ Synthetic TRPV1-agonist injectables based on capsaicin have undergone clinical trials for localized pain (eg, postoperative musculoskeletal pain); many patients experience pain relief, though benefit fades over weeks to months.^20,21

Use in Traditional Medicine—Capsicum peppers have been used to aid digestion and promote healing in gastrointestinal conditions, such as dyspepsia.²² The peppers are a source of important vitamins and minerals, including vitamins A, C, and E; many of the B complex vitamins; and magnesium, calcium, and iron.²³

Use as Cancer Therapy—Studies of the use of capsaicin in treating cancer have produced controversial results. In cell and animal models, capsaicin induces apoptosis through downregulation of the Bcl-2 protein; upregulation of oxidative stress, tribbles-related protein 3 (TRIB3), and caspase-3; and other pathways.^19,24-26 On the other hand, consumption of Capsicum peppers has been associated with cancer of the stomach and gallbladder.²⁷ Capsaicin might have anticarcinogenic properties, but its mechanism of action varies, depending on variables not fully understood.

Final Thoughts

Capsaicin is a neuropeptide-active compound found in Capsicum peppers that has many promising applications for use. However, dermatologists should be aware of the possibility of a skin reaction to this compound from handling peppers and using topical medicines. Exposure to capsaicin can cause irritant contact dermatitis that may require clinical care.

Cutaneous Manifestations

Capsicum peppers are used worldwide in preparing spicy dishes. Their active ingredient—capsaicin—is used as a topical medicine to treat localized pain. Capsicum peppers can cause irritant contact dermatitis with symptoms of erythema, cutaneous burning, and itch.¹

Irritant contact dermatitis is a common occupational skin disorder. Many cooks have experienced the sting of a chili pepper after contact with the hands or eyes. Cases of chronic exposure to Capsicum peppers with persistent burning and pain have been called Hunan hand syndrome.²Capsicum peppers also have induced allergic contact dermatitis in a food production worker.³

Capsicum peppers also are used in pepper spray, tear gas, and animal repellents because of their stinging properties. These agents usually cause cutaneous tingling and burning that soon resolves; however, a review of 31 studies showed that crowd-control methods with Capsicum-containing tear gas and pepper spray can cause moderate to severe skin damage such as a persistent skin rash or erythema, or even first-, second-, or third-degree burns.⁴

Topical application of capsaicin isolate is meant to cause burning and deplete local neuropeptides, with a cutaneous reaction that ranges from mild to intolerable.^5,6 Capsaicin also is found in other products. In one published case report, a 3-year-old boy broke out in facial urticaria when his mother kissed him on the cheek after she applied lip plumper containing capsaicin to her lips.⁷ Dermatologists should consider capsaicin an active ingredient that can irritate the skin in the garden, in the kitchen, and in topical products.

Obtaining Relief

Capsaicin-induced dermatitis can be relieved by washing the area with soap, detergent, baking soda, or oily compounds that act as solvents for the nonpolar capsaicin.⁸ Application of ice water or a high-potency topical steroid also may help. If the reaction is severe and persistent, a continuous stellate ganglion block may alleviate the pain of capsaicin-induced contact dermatitis.⁹

Identifying Features and Plant Facts

The Capsicum genus includes chili peppers, paprika, and red peppers. Capsicum peppers are native to tropical regions of the Americas (Figure). The use of Capsicum peppers in food can be traced to Indigenous peoples of Mexico as early as 7000 bc.¹⁰ On the Scoville scale, which was developed to quantify the hotness of foods and spices, Capsicum peppers are rated at approximately 2 million units; by comparison, jalapeño peppers have a Scoville score of 4500¹¹ and capsaicin isolate has a score of 16 million units. Capsicum species rank among the hottest peppers in the world.

Barker_Botanical.jpg

Capsicum belongs to the family Solanaceae, which includes tobacco, tomatoes, potatoes, and nightshade plants. There are many varieties of peppers in the Capsicum genus, with 5 domesticated species: Capsicum annuum, Capsicum baccatum, Capsicum chinense, Capsicum frutescens, and Capsicum pubescens. These include bell, poblano, cayenne, tabasco, habanero, and ají peppers, among others. Capsicum species grow as a shrub with flowers that rotate to stellate corollas and rounded berries of different sizes and colors.¹² Capsaicin and other alkaloids are concentrated in the fruit; therefore, Capsicum dermatitis is most commonly induced by contact with the flesh of peppers.

Capsaicin (8-methyl-6-nonanoyl vanillylamide) is a nonpolar phenol, which is why washing skin that has come in contact with capsaicin with water or vinegar alone is insufficient to solubilize it.¹³ Capsaicin binds to the transient receptor potential vanilloid 1 (TRPV1), a calcium channel on neurons that opens in response to heat. When bound, the channel opens at a lower temperature threshold and depolarizes nerve endings, leading to vasodilation and activation of sensory nerves.¹⁴ Substance P is released and the individual experiences a painful burning sensation. When purified capsaicin is frequently applied at an appropriate dose, synthesis of substance P is diminished, resulting in reduced local pain overall.¹⁵

Capsaicin does not affect neurons without TRPV1, and administration of capsaicin is not painful if given with anesthesia. An inappropriately high dose of capsaicin destroys cells in the epidermal barrier, resulting in water loss and inducing release of vasoactive peptides and inflammatory cytokines.¹ Careful handling of Capsicum peppers and capsaicin products can reduce the risk for irritation.

Medicinal Use

On-/Off-Label and Potential Uses—Capsaicin is US Food and Drug Administration approved for use in arthritis and musculoskeletal pain. It also is used to treat diabetic neuropathy,⁵ postherpetic neuralgia,⁶ psoriasis,¹⁶ and other conditions. Studies have shown that capsaicin might be useful in treating trigeminal neuralgia,¹⁷ fibromyalgia,¹⁸ migraines,¹⁴ cluster headaches,⁹ and HIV-associated distal sensory neuropathy.⁵

Delivery of Capsaicin—Capsaicin preferentially acts on C-fibers, which transmit dull, aching, chronic pain.¹⁹ The compound is available as a cream, lotion, and large bandage (for the lower back), as well as low- and high-dose patches. Capsaicin creams, lotions, and the low-dose patch are uncomfortable and must be applied for 4 to 6 weeks to take effect, which may impact patient adherence. The high-dose patch, which requires administration under local anesthesia by a health care worker, brings pain relief with a single use and improves adherence.¹¹ Synthetic TRPV1-agonist injectables based on capsaicin have undergone clinical trials for localized pain (eg, postoperative musculoskeletal pain); many patients experience pain relief, though benefit fades over weeks to months.^20,21

Use in Traditional Medicine—Capsicum peppers have been used to aid digestion and promote healing in gastrointestinal conditions, such as dyspepsia.²² The peppers are a source of important vitamins and minerals, including vitamins A, C, and E; many of the B complex vitamins; and magnesium, calcium, and iron.²³

Use as Cancer Therapy—Studies of the use of capsaicin in treating cancer have produced controversial results. In cell and animal models, capsaicin induces apoptosis through downregulation of the Bcl-2 protein; upregulation of oxidative stress, tribbles-related protein 3 (TRIB3), and caspase-3; and other pathways.^19,24-26 On the other hand, consumption of Capsicum peppers has been associated with cancer of the stomach and gallbladder.²⁷ Capsaicin might have anticarcinogenic properties, but its mechanism of action varies, depending on variables not fully understood.

Final Thoughts

Capsaicin is a neuropeptide-active compound found in Capsicum peppers that has many promising applications for use. However, dermatologists should be aware of the possibility of a skin reaction to this compound from handling peppers and using topical medicines. Exposure to capsaicin can cause irritant contact dermatitis that may require clinical care.

Etiology

Calcareous soils of central and southwest China are home to Primula obconica¹ (also known as German primrose and Libre Magenta).²Primula obconica was introduced to Europe in the 1880s, where it became a popular ornamental and decorative household plant (Figure).³ It also is a frequent resident of greenhouses.

Hassan.jpg

Primula obconica is a member of the family Primulaceae, which comprises semi-evergreen perennials. The genus name Primula is derived from Latin meaning “first”; obconica refers to the conelike shape of the plant’s vivid, cerise-red flowers.

Allergens From P obconica

The allergens primin (2-methoxy-6-pentyl-1,4-benzoquinone) and miconidin (2-methoxy-6-pentyl-1, 4-dihydroxybenzene) have been isolated from P obconica stems, leaves, and flowers. Allergies to P obconica are much more commonly detected in Europe than in the United States because the plant is part of standard allergen screening in dermatology clinics in Europe.⁴ In a British patch test study of 234 patients with hand dermatitis, 34 displayed immediate or delayed sensitization to P obconica allergens.⁵ However, in another study, researchers who surveyed the incidence of P obconica allergic contact dermatitis (CD) in the United Kingdom found a notable decline in the number of primin-positive patch tests from 1995 to 2000, which likely was attributable to a decrease in the number of plant retailers who stocked P obconica and the availability of primin-free varieties from 50% of suppliers.³ Furthermore, a study in the United States of 567 consecutive patch tests that included primin as part of standard screening found only 1 positive reaction, suggesting that routine patch testing for P obconica in the United States would have a low yield unless the patient has a relevant history.⁴

Cutaneous Presentation

Clinical features of P obconica–induced dermatitis include fingertip dermatitis, as well as facial, hand, and forearm dermatitis.⁶ Patients typically present with lichenification and fissuring of the fingertips; fingertip vesicular dermatitis; or linear erythematous streaks, vesicles, and bullae on the forearms, hands, and face. Vesicles and bullae can be hemorrhagic in patients with pompholyxlike lesions.⁷

Some patients have been reported to present with facial angioedema; the clinical diagnosis of CD can be challenging when facial edema is more prominent than eczema.⁶ Furthermore, in a reported case of P obconica CD, the patient’s vesicular hand dermatitis became pustular and spread to the face.⁸

Allergy Testing

Patch testing is performed with synthetic primin to detect allergens of P obconica in patients who are sensitive to them, which can be useful because Primula dermatitis can have variable presentations and cases can be missed if patch testing is not performed.⁹ Diagnostic mimics—herpes simplex, pompholyx, seborrheic dermatitis, and scabies—should be considered before patch testing.⁷

Prevention and Treatment

Preventive Measures—Ideally, once CD occurs in response to P obconica, handling of and other exposure to the plant should be halted; thus, prevention becomes the mainstay of treatment. Alternatively, when exposure is a necessary occupational hazard, nitrile gloves should be worn; allergenicity can be decreased by overwatering or introducing more primin-free varieties.^3,10

Cultivating the plant outdoors during the winter in milder climates can potentially decrease sensitivity because allergen production is lowest during cold months and highest during summer.¹¹ Because P obconica is commonly grown indoors, allergenicity can persist year-round.

Pharmacotherapy—Drawing on experience treating CD caused by other plants, acute and chronic P obconica CD are primarily treated with a topical steroid or, if the face or genitals are affected, with a steroid-sparing agent, such as tacrolimus.¹² A cool compress of water, saline, or Burow solution (aluminum acetate in water) can help decrease acute inflammation, especially in the setting of vesiculation.¹³

Mild CD also can be treated with a barrier cream and lipid-rich moisturizer. Their effectiveness likely is due to increased hydration and aiding impaired skin-barrier repair.¹⁴

Some success in treating chronic CD also has been reported with psoralen plus UVA and UVB light therapy, which function as local immunosuppressants, thus decreasing inflammation.¹⁵

Final Thoughts

Contact dermatitis caused by P obconica is common in Europe but less common in the United States and therefore often is underrecognized. Avoiding contact with the plant should be strongly recommended to allergic persons. Primula obconica allergic CD can be treated with a topical steroid.

Etiology

Calcareous soils of central and southwest China are home to Primula obconica¹ (also known as German primrose and Libre Magenta).²Primula obconica was introduced to Europe in the 1880s, where it became a popular ornamental and decorative household plant (Figure).³ It also is a frequent resident of greenhouses.

Hassan.jpg

Primula obconica is a member of the family Primulaceae, which comprises semi-evergreen perennials. The genus name Primula is derived from Latin meaning “first”; obconica refers to the conelike shape of the plant’s vivid, cerise-red flowers.

Allergens From P obconica

The allergens primin (2-methoxy-6-pentyl-1,4-benzoquinone) and miconidin (2-methoxy-6-pentyl-1, 4-dihydroxybenzene) have been isolated from P obconica stems, leaves, and flowers. Allergies to P obconica are much more commonly detected in Europe than in the United States because the plant is part of standard allergen screening in dermatology clinics in Europe.⁴ In a British patch test study of 234 patients with hand dermatitis, 34 displayed immediate or delayed sensitization to P obconica allergens.⁵ However, in another study, researchers who surveyed the incidence of P obconica allergic contact dermatitis (CD) in the United Kingdom found a notable decline in the number of primin-positive patch tests from 1995 to 2000, which likely was attributable to a decrease in the number of plant retailers who stocked P obconica and the availability of primin-free varieties from 50% of suppliers.³ Furthermore, a study in the United States of 567 consecutive patch tests that included primin as part of standard screening found only 1 positive reaction, suggesting that routine patch testing for P obconica in the United States would have a low yield unless the patient has a relevant history.⁴

Cutaneous Presentation

Clinical features of P obconica–induced dermatitis include fingertip dermatitis, as well as facial, hand, and forearm dermatitis.⁶ Patients typically present with lichenification and fissuring of the fingertips; fingertip vesicular dermatitis; or linear erythematous streaks, vesicles, and bullae on the forearms, hands, and face. Vesicles and bullae can be hemorrhagic in patients with pompholyxlike lesions.⁷

Some patients have been reported to present with facial angioedema; the clinical diagnosis of CD can be challenging when facial edema is more prominent than eczema.⁶ Furthermore, in a reported case of P obconica CD, the patient’s vesicular hand dermatitis became pustular and spread to the face.⁸

Allergy Testing

Patch testing is performed with synthetic primin to detect allergens of P obconica in patients who are sensitive to them, which can be useful because Primula dermatitis can have variable presentations and cases can be missed if patch testing is not performed.⁹ Diagnostic mimics—herpes simplex, pompholyx, seborrheic dermatitis, and scabies—should be considered before patch testing.⁷

Prevention and Treatment

Preventive Measures—Ideally, once CD occurs in response to P obconica, handling of and other exposure to the plant should be halted; thus, prevention becomes the mainstay of treatment. Alternatively, when exposure is a necessary occupational hazard, nitrile gloves should be worn; allergenicity can be decreased by overwatering or introducing more primin-free varieties.^3,10

Cultivating the plant outdoors during the winter in milder climates can potentially decrease sensitivity because allergen production is lowest during cold months and highest during summer.¹¹ Because P obconica is commonly grown indoors, allergenicity can persist year-round.

Pharmacotherapy—Drawing on experience treating CD caused by other plants, acute and chronic P obconica CD are primarily treated with a topical steroid or, if the face or genitals are affected, with a steroid-sparing agent, such as tacrolimus.¹² A cool compress of water, saline, or Burow solution (aluminum acetate in water) can help decrease acute inflammation, especially in the setting of vesiculation.¹³

Mild CD also can be treated with a barrier cream and lipid-rich moisturizer. Their effectiveness likely is due to increased hydration and aiding impaired skin-barrier repair.¹⁴

Some success in treating chronic CD also has been reported with psoralen plus UVA and UVB light therapy, which function as local immunosuppressants, thus decreasing inflammation.¹⁵

Final Thoughts

Contact dermatitis caused by P obconica is common in Europe but less common in the United States and therefore often is underrecognized. Avoiding contact with the plant should be strongly recommended to allergic persons. Primula obconica allergic CD can be treated with a topical steroid.

Etiology

Calcareous soils of central and southwest China are home to Primula obconica¹ (also known as German primrose and Libre Magenta).²Primula obconica was introduced to Europe in the 1880s, where it became a popular ornamental and decorative household plant (Figure).³ It also is a frequent resident of greenhouses.

Hassan.jpg

Primula obconica is a member of the family Primulaceae, which comprises semi-evergreen perennials. The genus name Primula is derived from Latin meaning “first”; obconica refers to the conelike shape of the plant’s vivid, cerise-red flowers.

Allergens From P obconica

The allergens primin (2-methoxy-6-pentyl-1,4-benzoquinone) and miconidin (2-methoxy-6-pentyl-1, 4-dihydroxybenzene) have been isolated from P obconica stems, leaves, and flowers. Allergies to P obconica are much more commonly detected in Europe than in the United States because the plant is part of standard allergen screening in dermatology clinics in Europe.⁴ In a British patch test study of 234 patients with hand dermatitis, 34 displayed immediate or delayed sensitization to P obconica allergens.⁵ However, in another study, researchers who surveyed the incidence of P obconica allergic contact dermatitis (CD) in the United Kingdom found a notable decline in the number of primin-positive patch tests from 1995 to 2000, which likely was attributable to a decrease in the number of plant retailers who stocked P obconica and the availability of primin-free varieties from 50% of suppliers.³ Furthermore, a study in the United States of 567 consecutive patch tests that included primin as part of standard screening found only 1 positive reaction, suggesting that routine patch testing for P obconica in the United States would have a low yield unless the patient has a relevant history.⁴

Cutaneous Presentation

Clinical features of P obconica–induced dermatitis include fingertip dermatitis, as well as facial, hand, and forearm dermatitis.⁶ Patients typically present with lichenification and fissuring of the fingertips; fingertip vesicular dermatitis; or linear erythematous streaks, vesicles, and bullae on the forearms, hands, and face. Vesicles and bullae can be hemorrhagic in patients with pompholyxlike lesions.⁷

Some patients have been reported to present with facial angioedema; the clinical diagnosis of CD can be challenging when facial edema is more prominent than eczema.⁶ Furthermore, in a reported case of P obconica CD, the patient’s vesicular hand dermatitis became pustular and spread to the face.⁸

Allergy Testing

Patch testing is performed with synthetic primin to detect allergens of P obconica in patients who are sensitive to them, which can be useful because Primula dermatitis can have variable presentations and cases can be missed if patch testing is not performed.⁹ Diagnostic mimics—herpes simplex, pompholyx, seborrheic dermatitis, and scabies—should be considered before patch testing.⁷

Prevention and Treatment

Preventive Measures—Ideally, once CD occurs in response to P obconica, handling of and other exposure to the plant should be halted; thus, prevention becomes the mainstay of treatment. Alternatively, when exposure is a necessary occupational hazard, nitrile gloves should be worn; allergenicity can be decreased by overwatering or introducing more primin-free varieties.^3,10

Cultivating the plant outdoors during the winter in milder climates can potentially decrease sensitivity because allergen production is lowest during cold months and highest during summer.¹¹ Because P obconica is commonly grown indoors, allergenicity can persist year-round.

Pharmacotherapy—Drawing on experience treating CD caused by other plants, acute and chronic P obconica CD are primarily treated with a topical steroid or, if the face or genitals are affected, with a steroid-sparing agent, such as tacrolimus.¹² A cool compress of water, saline, or Burow solution (aluminum acetate in water) can help decrease acute inflammation, especially in the setting of vesiculation.¹³

Mild CD also can be treated with a barrier cream and lipid-rich moisturizer. Their effectiveness likely is due to increased hydration and aiding impaired skin-barrier repair.¹⁴

Some success in treating chronic CD also has been reported with psoralen plus UVA and UVB light therapy, which function as local immunosuppressants, thus decreasing inflammation.¹⁵

Final Thoughts

Contact dermatitis caused by P obconica is common in Europe but less common in the United States and therefore often is underrecognized. Avoiding contact with the plant should be strongly recommended to allergic persons. Primula obconica allergic CD can be treated with a topical steroid.

Contact dermatitis is a common problem in the floral bulb industry and is considered an occupational disease. Daffodils (Narcissus species)(Figure) are thought to be the most common cause of irritant contact dermatitis among florists.¹

Clinical Importance

Picking daffodils can start as early as October, when the flowers are still closed. The picker’s hand slides down the stem to snap the stalk at the base. This potentially traumatic maneuver to the web of the fingers leads to abrasions, which are irritated by the sap and cause granulomatous sores and paronychia. An experienced picker can pick 20,000 flowers a day, leading to extensive contact with sap.²

Eczematous or granulomatous rash on the arms also is seen as the sap irritates the wrist and forearm. The pickers often hold the flowers until a bunch of 10 has been collected. The 10 flowers are held together by a rubber band and stacked along the arm, the chin, and the axilla, causing the rash to extend to those areas. Sap also can be transferred by the hand to other parts of the body, such as the face. In men, sap can be transferred to the genitalia as the men urinate in the field.

Narcissus also can cause poisoning if ingested by humans or animals. Researchers who analyzed calls made to the New Zealand Natural Poisons Centre between 2003 and 2010 determined that daffodil was the 11th most common call for plant-related poisoning.³

Although the severity of plant poisoning often is low due to the small amount of plant material usually consumed, more severe poisoning can occur when the plant is eaten for medicinal purposes or mistaken for an edible plant.³ Vomiting, respiratory symptoms, abdominal pain, diarrhea, trembling, and convulsions can occur when daffodils are ingested. Death has been reported due to ingestion of the bulbs.⁴

In February 2010, 10 children aged 10 and 11 years and their 22-year-old guide presented to an emergency department in Israel after ingesting Narcissus bulbs, which were mistakenly believed to be the bulbs of onions.⁴ Eight children and the guide vomited. One child and the guide reported abdominal pain. All were discharged in stable condition after 4 hours of observation.⁴

Clinical Manifestations

Daffodil rash or lily rash was first described in 1910.⁵ The typical rash presents as dryness, fissures, scaling, and erythema of the fingertips, hands, and forearms, often with subungual hyperkeratosis. Vesicles and pustules may be seen. The rash may extend to other areas of the body, including the face.⁶

Use of protective gloves and clothing to avoid contact with the plant is recommended.² Treatment includes stopping contact with the irritant, eye irrigation, and supportive measures (airway, breathing, and circulation). Activated charcoal can be helpful if used within 1 hour after ingestion but is contraindicated in vomiting patients.⁴

Identifying Features

The genus Narcissus is in the family Amaryllidaceae and contains ornamental plants, including daffodil (trumpet Narcissus, Narcissus pseudonarcissus), jonquil (Narcissus jonquilla), and poet’s narcissus (Narcissus poeticus). Most species are perennial; the plant emerges from a bulb in spring. Leaves originate from the base of the plant and range from 5-cm to 1.2-meters long, depending on the species. The flowers span a range of shapes and colors—from a trumpet (the daffodil) to a ringlike cup (poet’s Narcissus) and in yellow, white, and pink.⁷

Distribution and Plant Facts

Distribution—There are approximately 80 to 100 wild Narcissus species, which are found in southwestern Europe, North Africa, the Balkan Peninsula, Italy, and France. There are more than 27,000 Narcissus cultivars registered in the International Daffodil Register.⁸

Plant Facts—The daffodil is the national flower of Wales. It also is often used to depict hope and joy and is the symbol of cancer charities in many countries.⁹

The name Narcissus is believed to have originated from Greek mythology. A handsome youth, Narcissus, fell in love with his own reflection, for which the gods punished him by turning him into a flower.¹⁰

Another theory states that Narcissus is derived from the Greek word narkao (to benumb) due to its narcotic properties. When an open wound is subjected to an extract of the bulb, numbness of the entire nervous system is said to occur as well as paralysis of the heart. This narcotic effect led Socrates to refer to the Narcissus plant as the “chaplet of the infernal gods.”¹¹

Narcissus is an important flower in various ethnic rituals. The Greeks often planted daffodils near tombs. In Muslim culture, white is believed to be the symbol of good and purity; Narcissus was one of the most common white-flowered plants found in Muslim graveyards.¹²

Medicinal Qualities and Uses—Narcissus species have been used as medicinal plants for a variety of ailments. For example, Narcissus tazetta contains flavonoids, alkaloids, saponins, tannins, cardiac glycosides, oil, steroids, terpenoids, and anthraquinones that contribute to its antibacterial, antifungal, antiviral, antimalarial, anticancer, antioxidant, dermatologic, cardiovascular, immunomodulatory, and acetylcholinesterase inhibitory effects.¹³ In a study, chloroform extracts from N tazetta bulbs were found to be more active than doxorubicin against hepatocellular and colon cancer cell lines.¹⁴

More than 500 alkaloids have been isolated from the Narcissus genus.¹⁵ In 2001, the US Food and Drug Administration approved one of the alkaloids, galantamine, for the treatment of mild to moderate stages of Alzheimer disease.¹⁶ Galantamine selectively and reversibly inhibits acetylcholinesterase, the enzyme believed responsible for neurodegeneration seen in Alzheimer disease. Plants are the main source of galantamine, despite the ability of pharmaceutical companies to synthesize the compound. Galantamine hydrobromide is sold by prescription (Razadyne [Janssen Pharmaceuticals, Inc]); generic formulations approved by the US Food and Drug Administration have been produced by more than 15 pharmaceutical companies.^17,18

Irritant and Allergen

Sap found in the bulbs and hollow stems of Narcissus contains calcium oxalate crystals, or raphides. The minute, needle-shaped calcium oxalate crystals are believed to be a waste product of cellular metabolism.¹⁹ When the plant structure is compromised by pickers snapping the stalk, the sharp crystals penetrate the skin to cause an irritant contact dermatitis.

Relevant Research—A study used electron microscopy to characterize the structure of raphides from various plants,² though not from Narcissus species; the structure of each raphide was then compared to the degree of irritation it produced. The researchers concluded that more elongated crystals (those containing barbs) produce a greater degree of irritation. Narcissus species are known to cause varying degrees of skin irritation: For example, N tazetta rarely causes skin irritation, whereas N pseudonarcissi (daffodil) tends to cause remarkably more skin irritation.²

Allergic reactions to and strong toxicity from Narcissus species are not well understood. In a study, only 2 alkaloids—homolycorine and masonin—produced a weakly positive reaction in patch tests on sensitized guinea pigs, which correlates with the finding of a different study, in which only 2 of 12 patients whose findings were examined over 14 years had a positive patch test for Narcissus.^20,21

However, IgE-mediated allergies indicative of an allergic response to Narcissus have been reported. A study isolated an allergenic protein, narcin, from bulbs of N tazetta. Narcin is a 13-kDa protein with potent allergenic effects capable of inducing production of proinflammatory cytokines and increasing IgE levels in mononuclear cells in peripheral blood.²²

More research is required to find and understand the compounds responsible for causing an allergic reaction to Narcissus.

Contact dermatitis is a common problem in the floral bulb industry and is considered an occupational disease. Daffodils (Narcissus species)(Figure) are thought to be the most common cause of irritant contact dermatitis among florists.¹

Clinical Importance

Picking daffodils can start as early as October, when the flowers are still closed. The picker’s hand slides down the stem to snap the stalk at the base. This potentially traumatic maneuver to the web of the fingers leads to abrasions, which are irritated by the sap and cause granulomatous sores and paronychia. An experienced picker can pick 20,000 flowers a day, leading to extensive contact with sap.²

Eczematous or granulomatous rash on the arms also is seen as the sap irritates the wrist and forearm. The pickers often hold the flowers until a bunch of 10 has been collected. The 10 flowers are held together by a rubber band and stacked along the arm, the chin, and the axilla, causing the rash to extend to those areas. Sap also can be transferred by the hand to other parts of the body, such as the face. In men, sap can be transferred to the genitalia as the men urinate in the field.

Narcissus also can cause poisoning if ingested by humans or animals. Researchers who analyzed calls made to the New Zealand Natural Poisons Centre between 2003 and 2010 determined that daffodil was the 11th most common call for plant-related poisoning.³

Although the severity of plant poisoning often is low due to the small amount of plant material usually consumed, more severe poisoning can occur when the plant is eaten for medicinal purposes or mistaken for an edible plant.³ Vomiting, respiratory symptoms, abdominal pain, diarrhea, trembling, and convulsions can occur when daffodils are ingested. Death has been reported due to ingestion of the bulbs.⁴

In February 2010, 10 children aged 10 and 11 years and their 22-year-old guide presented to an emergency department in Israel after ingesting Narcissus bulbs, which were mistakenly believed to be the bulbs of onions.⁴ Eight children and the guide vomited. One child and the guide reported abdominal pain. All were discharged in stable condition after 4 hours of observation.⁴

Clinical Manifestations

Daffodil rash or lily rash was first described in 1910.⁵ The typical rash presents as dryness, fissures, scaling, and erythema of the fingertips, hands, and forearms, often with subungual hyperkeratosis. Vesicles and pustules may be seen. The rash may extend to other areas of the body, including the face.⁶

Use of protective gloves and clothing to avoid contact with the plant is recommended.² Treatment includes stopping contact with the irritant, eye irrigation, and supportive measures (airway, breathing, and circulation). Activated charcoal can be helpful if used within 1 hour after ingestion but is contraindicated in vomiting patients.⁴

Identifying Features

The genus Narcissus is in the family Amaryllidaceae and contains ornamental plants, including daffodil (trumpet Narcissus, Narcissus pseudonarcissus), jonquil (Narcissus jonquilla), and poet’s narcissus (Narcissus poeticus). Most species are perennial; the plant emerges from a bulb in spring. Leaves originate from the base of the plant and range from 5-cm to 1.2-meters long, depending on the species. The flowers span a range of shapes and colors—from a trumpet (the daffodil) to a ringlike cup (poet’s Narcissus) and in yellow, white, and pink.⁷

Distribution and Plant Facts

Distribution—There are approximately 80 to 100 wild Narcissus species, which are found in southwestern Europe, North Africa, the Balkan Peninsula, Italy, and France. There are more than 27,000 Narcissus cultivars registered in the International Daffodil Register.⁸

Plant Facts—The daffodil is the national flower of Wales. It also is often used to depict hope and joy and is the symbol of cancer charities in many countries.⁹

The name Narcissus is believed to have originated from Greek mythology. A handsome youth, Narcissus, fell in love with his own reflection, for which the gods punished him by turning him into a flower.¹⁰

Another theory states that Narcissus is derived from the Greek word narkao (to benumb) due to its narcotic properties. When an open wound is subjected to an extract of the bulb, numbness of the entire nervous system is said to occur as well as paralysis of the heart. This narcotic effect led Socrates to refer to the Narcissus plant as the “chaplet of the infernal gods.”¹¹

Narcissus is an important flower in various ethnic rituals. The Greeks often planted daffodils near tombs. In Muslim culture, white is believed to be the symbol of good and purity; Narcissus was one of the most common white-flowered plants found in Muslim graveyards.¹²

Medicinal Qualities and Uses—Narcissus species have been used as medicinal plants for a variety of ailments. For example, Narcissus tazetta contains flavonoids, alkaloids, saponins, tannins, cardiac glycosides, oil, steroids, terpenoids, and anthraquinones that contribute to its antibacterial, antifungal, antiviral, antimalarial, anticancer, antioxidant, dermatologic, cardiovascular, immunomodulatory, and acetylcholinesterase inhibitory effects.¹³ In a study, chloroform extracts from N tazetta bulbs were found to be more active than doxorubicin against hepatocellular and colon cancer cell lines.¹⁴

More than 500 alkaloids have been isolated from the Narcissus genus.¹⁵ In 2001, the US Food and Drug Administration approved one of the alkaloids, galantamine, for the treatment of mild to moderate stages of Alzheimer disease.¹⁶ Galantamine selectively and reversibly inhibits acetylcholinesterase, the enzyme believed responsible for neurodegeneration seen in Alzheimer disease. Plants are the main source of galantamine, despite the ability of pharmaceutical companies to synthesize the compound. Galantamine hydrobromide is sold by prescription (Razadyne [Janssen Pharmaceuticals, Inc]); generic formulations approved by the US Food and Drug Administration have been produced by more than 15 pharmaceutical companies.^17,18

Irritant and Allergen

Sap found in the bulbs and hollow stems of Narcissus contains calcium oxalate crystals, or raphides. The minute, needle-shaped calcium oxalate crystals are believed to be a waste product of cellular metabolism.¹⁹ When the plant structure is compromised by pickers snapping the stalk, the sharp crystals penetrate the skin to cause an irritant contact dermatitis.

Relevant Research—A study used electron microscopy to characterize the structure of raphides from various plants,² though not from Narcissus species; the structure of each raphide was then compared to the degree of irritation it produced. The researchers concluded that more elongated crystals (those containing barbs) produce a greater degree of irritation. Narcissus species are known to cause varying degrees of skin irritation: For example, N tazetta rarely causes skin irritation, whereas N pseudonarcissi (daffodil) tends to cause remarkably more skin irritation.²

Allergic reactions to and strong toxicity from Narcissus species are not well understood. In a study, only 2 alkaloids—homolycorine and masonin—produced a weakly positive reaction in patch tests on sensitized guinea pigs, which correlates with the finding of a different study, in which only 2 of 12 patients whose findings were examined over 14 years had a positive patch test for Narcissus.^20,21

However, IgE-mediated allergies indicative of an allergic response to Narcissus have been reported. A study isolated an allergenic protein, narcin, from bulbs of N tazetta. Narcin is a 13-kDa protein with potent allergenic effects capable of inducing production of proinflammatory cytokines and increasing IgE levels in mononuclear cells in peripheral blood.²²

More research is required to find and understand the compounds responsible for causing an allergic reaction to Narcissus.

Contact dermatitis is a common problem in the floral bulb industry and is considered an occupational disease. Daffodils (Narcissus species)(Figure) are thought to be the most common cause of irritant contact dermatitis among florists.¹

Clinical Importance

Picking daffodils can start as early as October, when the flowers are still closed. The picker’s hand slides down the stem to snap the stalk at the base. This potentially traumatic maneuver to the web of the fingers leads to abrasions, which are irritated by the sap and cause granulomatous sores and paronychia. An experienced picker can pick 20,000 flowers a day, leading to extensive contact with sap.²

Eczematous or granulomatous rash on the arms also is seen as the sap irritates the wrist and forearm. The pickers often hold the flowers until a bunch of 10 has been collected. The 10 flowers are held together by a rubber band and stacked along the arm, the chin, and the axilla, causing the rash to extend to those areas. Sap also can be transferred by the hand to other parts of the body, such as the face. In men, sap can be transferred to the genitalia as the men urinate in the field.

Narcissus also can cause poisoning if ingested by humans or animals. Researchers who analyzed calls made to the New Zealand Natural Poisons Centre between 2003 and 2010 determined that daffodil was the 11th most common call for plant-related poisoning.³

Although the severity of plant poisoning often is low due to the small amount of plant material usually consumed, more severe poisoning can occur when the plant is eaten for medicinal purposes or mistaken for an edible plant.³ Vomiting, respiratory symptoms, abdominal pain, diarrhea, trembling, and convulsions can occur when daffodils are ingested. Death has been reported due to ingestion of the bulbs.⁴

In February 2010, 10 children aged 10 and 11 years and their 22-year-old guide presented to an emergency department in Israel after ingesting Narcissus bulbs, which were mistakenly believed to be the bulbs of onions.⁴ Eight children and the guide vomited. One child and the guide reported abdominal pain. All were discharged in stable condition after 4 hours of observation.⁴

Clinical Manifestations

Daffodil rash or lily rash was first described in 1910.⁵ The typical rash presents as dryness, fissures, scaling, and erythema of the fingertips, hands, and forearms, often with subungual hyperkeratosis. Vesicles and pustules may be seen. The rash may extend to other areas of the body, including the face.⁶

Use of protective gloves and clothing to avoid contact with the plant is recommended.² Treatment includes stopping contact with the irritant, eye irrigation, and supportive measures (airway, breathing, and circulation). Activated charcoal can be helpful if used within 1 hour after ingestion but is contraindicated in vomiting patients.⁴

Identifying Features

The genus Narcissus is in the family Amaryllidaceae and contains ornamental plants, including daffodil (trumpet Narcissus, Narcissus pseudonarcissus), jonquil (Narcissus jonquilla), and poet’s narcissus (Narcissus poeticus). Most species are perennial; the plant emerges from a bulb in spring. Leaves originate from the base of the plant and range from 5-cm to 1.2-meters long, depending on the species. The flowers span a range of shapes and colors—from a trumpet (the daffodil) to a ringlike cup (poet’s Narcissus) and in yellow, white, and pink.⁷

Distribution and Plant Facts

Distribution—There are approximately 80 to 100 wild Narcissus species, which are found in southwestern Europe, North Africa, the Balkan Peninsula, Italy, and France. There are more than 27,000 Narcissus cultivars registered in the International Daffodil Register.⁸

Plant Facts—The daffodil is the national flower of Wales. It also is often used to depict hope and joy and is the symbol of cancer charities in many countries.⁹

The name Narcissus is believed to have originated from Greek mythology. A handsome youth, Narcissus, fell in love with his own reflection, for which the gods punished him by turning him into a flower.¹⁰

Another theory states that Narcissus is derived from the Greek word narkao (to benumb) due to its narcotic properties. When an open wound is subjected to an extract of the bulb, numbness of the entire nervous system is said to occur as well as paralysis of the heart. This narcotic effect led Socrates to refer to the Narcissus plant as the “chaplet of the infernal gods.”¹¹

Narcissus is an important flower in various ethnic rituals. The Greeks often planted daffodils near tombs. In Muslim culture, white is believed to be the symbol of good and purity; Narcissus was one of the most common white-flowered plants found in Muslim graveyards.¹²

Medicinal Qualities and Uses—Narcissus species have been used as medicinal plants for a variety of ailments. For example, Narcissus tazetta contains flavonoids, alkaloids, saponins, tannins, cardiac glycosides, oil, steroids, terpenoids, and anthraquinones that contribute to its antibacterial, antifungal, antiviral, antimalarial, anticancer, antioxidant, dermatologic, cardiovascular, immunomodulatory, and acetylcholinesterase inhibitory effects.¹³ In a study, chloroform extracts from N tazetta bulbs were found to be more active than doxorubicin against hepatocellular and colon cancer cell lines.¹⁴

More than 500 alkaloids have been isolated from the Narcissus genus.¹⁵ In 2001, the US Food and Drug Administration approved one of the alkaloids, galantamine, for the treatment of mild to moderate stages of Alzheimer disease.¹⁶ Galantamine selectively and reversibly inhibits acetylcholinesterase, the enzyme believed responsible for neurodegeneration seen in Alzheimer disease. Plants are the main source of galantamine, despite the ability of pharmaceutical companies to synthesize the compound. Galantamine hydrobromide is sold by prescription (Razadyne [Janssen Pharmaceuticals, Inc]); generic formulations approved by the US Food and Drug Administration have been produced by more than 15 pharmaceutical companies.^17,18

Irritant and Allergen

Sap found in the bulbs and hollow stems of Narcissus contains calcium oxalate crystals, or raphides. The minute, needle-shaped calcium oxalate crystals are believed to be a waste product of cellular metabolism.¹⁹ When the plant structure is compromised by pickers snapping the stalk, the sharp crystals penetrate the skin to cause an irritant contact dermatitis.

Relevant Research—A study used electron microscopy to characterize the structure of raphides from various plants,² though not from Narcissus species; the structure of each raphide was then compared to the degree of irritation it produced. The researchers concluded that more elongated crystals (those containing barbs) produce a greater degree of irritation. Narcissus species are known to cause varying degrees of skin irritation: For example, N tazetta rarely causes skin irritation, whereas N pseudonarcissi (daffodil) tends to cause remarkably more skin irritation.²

Allergic reactions to and strong toxicity from Narcissus species are not well understood. In a study, only 2 alkaloids—homolycorine and masonin—produced a weakly positive reaction in patch tests on sensitized guinea pigs, which correlates with the finding of a different study, in which only 2 of 12 patients whose findings were examined over 14 years had a positive patch test for Narcissus.^20,21

However, IgE-mediated allergies indicative of an allergic response to Narcissus have been reported. A study isolated an allergenic protein, narcin, from bulbs of N tazetta. Narcin is a 13-kDa protein with potent allergenic effects capable of inducing production of proinflammatory cytokines and increasing IgE levels in mononuclear cells in peripheral blood.²²

More research is required to find and understand the compounds responsible for causing an allergic reaction to Narcissus.

Reactions to poison ivy, poison oak, and poison sumac, which affect 10 to 50 million Americans a year,¹ are classified as Toxicodendron dermatitis; 50% to 75% of US adults are clinically sensitive to these plants.² Furthermore, people of all ethnicities, skin types, and ages residing in most US geographical regions are at risk.³ Allergenicity is caused by urushiol, which is found in members of the Anacardiaceae family.⁴ Once absorbed, urushiol causes a type IV hypersensitivity reaction in those who are susceptible.⁵

Cutaneous Manifestations

Toxicodendron dermatitis presents with an acute eczematous eruption characterized by streaks of intensely pruritic and erythematous papules and vesicles (Figure 1). Areas of involvement are characterized by sharp margins that follow the pattern of contact made by the plant’s leaves, berries, stems, and vines.⁶ The fluid content of the vesicles is not antigenic and cannot cause subsequent transmission to oneself or others.³ A person with prior contact to the plant who becomes sensitized develops an eruption 24 to 48 hours after subsequent contact with the plant; peak severity manifests 1 to 14 days later.⁷

Hunt_1.jpg

When left untreated, the eruption can last 3 weeks. If the plant is burned, urushiol can be aerosolized in smoke, causing respiratory tract inflammation and generalized dermatitis, which has been reported among wildland firefighters.² Long-term complications from an outbreak are limited but can include postinflammatory hyperpigmentation and secondary bacterial infection.⁸ Rare reports of nephrotic syndrome also have appeared in the literature.⁹Toxicodendron dermatitis can present distinctively as so-called black dot dermatitis.⁶

Nomenclature

Poison ivy, poison oak, and poison sumac are members of the family Anacardiaceae and genus Toxicodendron,⁶ derived from the Greek words toxikos (poison) and dendron (tree).¹⁰

Distribution

Toxicodendron plants characteristically are found in various regions of the United States. Poison ivy is the most common and is comprised of 2 species: Toxicodendron rydbergii and Toxicodendron radicans. Toxicodendron rydbergii is a nonclimbing dwarf shrub typically found in the northern and western United States. Toxicodendron radicans is a climbing vine found in the eastern United States. Poison oak also is comprised of 2 species—Toxicodendron toxicarium and Toxicodendron diversilobum—and is more common in the western United States. Poison sumac (also known as Toxicodendron vernix) is a small shrub that grows in moist swampy areas. It has a predilection for marshes of the eastern and southeastern United States.^6,11

Identifying Features

Educating patients on how to identify poison ivy can play a key role in avoidance, which is the most important step in preventing Toxicodendron dermatitis. A challenge in identification of poison ivy is the plant’s variable appearance; it grows as a small shrub, low-lying vine, or vine that climbs other trees.

As the vine matures, it develops tiny, rough, “hairy” rootlets—hence the saying, “Hairy vine, no friend of mine!” Rootlets help the plant attach to trees growing near a water source. Vines can reach a diameter of 3 inches. From mature vines, solitary stems extend 1 to 2 inches with 3 characteristic leaves at the terminus (Figure 2), prompting another classic saying, “Leaves of 3, let it be!”¹²

Hunt_2.jpg

Poison oak is characterized by 3 to 5 leaflets. Poison sumac has 7 to 13 pointed, smooth-edged leaves.⁶

Dermatitis-Inducing Plant Parts

The primary allergenic component of Toxicodendron plants is urushiol, a resinous sap found in stems, roots, leaves, and skins of the fruits. These components must be damaged or bruised to release the allergen; slight contact with an uninjured plant part might not lead to harm.^2,13 Some common forms of transmission include skin contact, ingestion, inhalation of smoke from burning plants, and contact with skin through contaminated items, such as clothing, animals, and tools.¹⁴

Allergens

The catecholic ring and aliphatic chain of the urushiol molecule are allergenic.¹⁵ The degree of saturation and length of the side chains vary with different catechols. Urushiol displays cross-reactivity with poison ivy, poison oak, and poison sumac. Urushiol from these plants differs only slightly in structure; therefore, sensitization to one causes sensitization to all. There also is cross-reactivity between different members of the Anacardiaceae family, including Anacardium occidentale (tropical cashew nut), Mangifera indica (tropical mango tree), Ginkgo biloba (ginkgo tree), and Semecarpus anacardium (Indian marking nut tree).¹²

Poison ivy, poison oak, and poison sumac cause allergic contact dermatitis as a type IV hypersensitivity reaction. First, urushiol binds and penetrates the skin, where it is oxidized to quinone intermediates and bound to haptens. Then, the intermediates bind surface proteins on antigen-presenting cells, specifically Langerhans cells in the epidermis and dermis.⁵

Presentation of nonpeptide antigens, such as urushiol, to T cells requires expression of langerin (also known as CD207) and CD1a.¹⁶ Langerin is a C-type lectin that causes formation of Birbeck granules; CD1a is a major histocompatibility complex class I molecule found in Birbeck granules.^5,17 After Langerhans cells internalize and process the urushiol self-hapten neoantigen, it is presented to CD4⁺ T cells.⁶ These cells then expand to form circulating activated T-effector and T-memory lymphocytes.¹⁸

The molecular link that occurs between the hapten and carrier protein determines the response. When linked by an amino nucleophile, selective induction of T-effector cells ensues, resulting in allergic contact dermatitis. When linked by a sulfhydryl bond, selective induction of suppressor cells occurs, resulting in a reduced allergic contact dermatitis response.¹⁹ In the case of activation of T-effector cells, a cell-mediated cytotoxic immune response is generated that destroys epidermal cells and dermal vasculature.² The incidence and intensity of poison ivy sensitivity decline proportionally with age and the absence of continued exposure.²⁰

Preventive Action—Patients should be counseled that if contact between plant and skin occurs, it is important to remove contaminated clothing or objects and wash them with soap to prevent additional exposure.^14,21 Areas of the skin that made contact with the plant should be washed with water as soon as possible; after 30 minutes, urushiol has sufficiently penetrated to cause a reaction.² Forceful unidirectional washing with a damp washcloth and liquid dishwashing soap is recommended.²²

Several barrier creams are commercially available to help prevent absorption or to deactivate the urushiol antigen. These products are used widely by forestry workers and wildland firefighters.²³ One such barrier cream is bentoquatam (sold as various trade names), an organoclay compound made of quaternium-18 bentonite that interferes with absorption of the allergen by acting as a physical blocker.²⁴

Treatment

After Toxicodendron dermatitis develops, several treatments are available to help manage symptoms. Calamine lotion can be used to help dry weeping lesions.^25,26 Topical steroids can be used to help control pruritus and alleviate inflammation. High-potency topical corticosteroids such as clobetasol and mid-potency steroids such as triamcinolone can be used. Topical anesthetics (eg, benzocaine, pramoxine, benzyl alcohol) might provide symptomatic relief.^27,28

Oral antihistamines can allow for better sleep by providing sedation but do not target the pruritus of poison ivy dermatitis, which is not histamine mediated.^29,30 Systemic corticosteroids usually are considered in more severe dermatitis—when 20% or more of the body surface area is involved; blistering and itching are severe; or the face, hands, or genitalia are involved.^31,32

Clinical Uses

Therapeutic uses for poison ivy have been explored extensively. In 1892, Dakin³³ reported that ingestion of leaves by Native Americans reduced the incidence and severity of skin lesions after contact with poison ivy. Consumption of poison ivy was further studied by Epstein and colleagues³⁴ in 1974; they concluded that ingestion of a large amount of urushiol over a period of 3 months or longer may help with hyposensitization—but not complete desensitization—to contact with poison ivy. However, the risk for adverse effects is thought to outweigh benefits because ingestion can cause perianal dermatitis, mucocutaneous sequelae, and systemic contact dermatitis.²

Although the use of Toxicodendron plants in modern-day medicine is limited, development of a vaccine (immunotherapy) against Toxicodendron dermatitis offers an exciting opportunity for further research.

Reactions to poison ivy, poison oak, and poison sumac, which affect 10 to 50 million Americans a year,¹ are classified as Toxicodendron dermatitis; 50% to 75% of US adults are clinically sensitive to these plants.² Furthermore, people of all ethnicities, skin types, and ages residing in most US geographical regions are at risk.³ Allergenicity is caused by urushiol, which is found in members of the Anacardiaceae family.⁴ Once absorbed, urushiol causes a type IV hypersensitivity reaction in those who are susceptible.⁵

Cutaneous Manifestations

Toxicodendron dermatitis presents with an acute eczematous eruption characterized by streaks of intensely pruritic and erythematous papules and vesicles (Figure 1). Areas of involvement are characterized by sharp margins that follow the pattern of contact made by the plant’s leaves, berries, stems, and vines.⁶ The fluid content of the vesicles is not antigenic and cannot cause subsequent transmission to oneself or others.³ A person with prior contact to the plant who becomes sensitized develops an eruption 24 to 48 hours after subsequent contact with the plant; peak severity manifests 1 to 14 days later.⁷

Hunt_1.jpg

When left untreated, the eruption can last 3 weeks. If the plant is burned, urushiol can be aerosolized in smoke, causing respiratory tract inflammation and generalized dermatitis, which has been reported among wildland firefighters.² Long-term complications from an outbreak are limited but can include postinflammatory hyperpigmentation and secondary bacterial infection.⁸ Rare reports of nephrotic syndrome also have appeared in the literature.⁹Toxicodendron dermatitis can present distinctively as so-called black dot dermatitis.⁶

Nomenclature

Poison ivy, poison oak, and poison sumac are members of the family Anacardiaceae and genus Toxicodendron,⁶ derived from the Greek words toxikos (poison) and dendron (tree).¹⁰

Distribution

Toxicodendron plants characteristically are found in various regions of the United States. Poison ivy is the most common and is comprised of 2 species: Toxicodendron rydbergii and Toxicodendron radicans. Toxicodendron rydbergii is a nonclimbing dwarf shrub typically found in the northern and western United States. Toxicodendron radicans is a climbing vine found in the eastern United States. Poison oak also is comprised of 2 species—Toxicodendron toxicarium and Toxicodendron diversilobum—and is more common in the western United States. Poison sumac (also known as Toxicodendron vernix) is a small shrub that grows in moist swampy areas. It has a predilection for marshes of the eastern and southeastern United States.^6,11

Identifying Features

Educating patients on how to identify poison ivy can play a key role in avoidance, which is the most important step in preventing Toxicodendron dermatitis. A challenge in identification of poison ivy is the plant’s variable appearance; it grows as a small shrub, low-lying vine, or vine that climbs other trees.

As the vine matures, it develops tiny, rough, “hairy” rootlets—hence the saying, “Hairy vine, no friend of mine!” Rootlets help the plant attach to trees growing near a water source. Vines can reach a diameter of 3 inches. From mature vines, solitary stems extend 1 to 2 inches with 3 characteristic leaves at the terminus (Figure 2), prompting another classic saying, “Leaves of 3, let it be!”¹²

Hunt_2.jpg

Poison oak is characterized by 3 to 5 leaflets. Poison sumac has 7 to 13 pointed, smooth-edged leaves.⁶

Dermatitis-Inducing Plant Parts

The primary allergenic component of Toxicodendron plants is urushiol, a resinous sap found in stems, roots, leaves, and skins of the fruits. These components must be damaged or bruised to release the allergen; slight contact with an uninjured plant part might not lead to harm.^2,13 Some common forms of transmission include skin contact, ingestion, inhalation of smoke from burning plants, and contact with skin through contaminated items, such as clothing, animals, and tools.¹⁴

Allergens

The catecholic ring and aliphatic chain of the urushiol molecule are allergenic.¹⁵ The degree of saturation and length of the side chains vary with different catechols. Urushiol displays cross-reactivity with poison ivy, poison oak, and poison sumac. Urushiol from these plants differs only slightly in structure; therefore, sensitization to one causes sensitization to all. There also is cross-reactivity between different members of the Anacardiaceae family, including Anacardium occidentale (tropical cashew nut), Mangifera indica (tropical mango tree), Ginkgo biloba (ginkgo tree), and Semecarpus anacardium (Indian marking nut tree).¹²

Poison ivy, poison oak, and poison sumac cause allergic contact dermatitis as a type IV hypersensitivity reaction. First, urushiol binds and penetrates the skin, where it is oxidized to quinone intermediates and bound to haptens. Then, the intermediates bind surface proteins on antigen-presenting cells, specifically Langerhans cells in the epidermis and dermis.⁵

Presentation of nonpeptide antigens, such as urushiol, to T cells requires expression of langerin (also known as CD207) and CD1a.¹⁶ Langerin is a C-type lectin that causes formation of Birbeck granules; CD1a is a major histocompatibility complex class I molecule found in Birbeck granules.^5,17 After Langerhans cells internalize and process the urushiol self-hapten neoantigen, it is presented to CD4⁺ T cells.⁶ These cells then expand to form circulating activated T-effector and T-memory lymphocytes.¹⁸

The molecular link that occurs between the hapten and carrier protein determines the response. When linked by an amino nucleophile, selective induction of T-effector cells ensues, resulting in allergic contact dermatitis. When linked by a sulfhydryl bond, selective induction of suppressor cells occurs, resulting in a reduced allergic contact dermatitis response.¹⁹ In the case of activation of T-effector cells, a cell-mediated cytotoxic immune response is generated that destroys epidermal cells and dermal vasculature.² The incidence and intensity of poison ivy sensitivity decline proportionally with age and the absence of continued exposure.²⁰

Preventive Action—Patients should be counseled that if contact between plant and skin occurs, it is important to remove contaminated clothing or objects and wash them with soap to prevent additional exposure.^14,21 Areas of the skin that made contact with the plant should be washed with water as soon as possible; after 30 minutes, urushiol has sufficiently penetrated to cause a reaction.² Forceful unidirectional washing with a damp washcloth and liquid dishwashing soap is recommended.²²

Several barrier creams are commercially available to help prevent absorption or to deactivate the urushiol antigen. These products are used widely by forestry workers and wildland firefighters.²³ One such barrier cream is bentoquatam (sold as various trade names), an organoclay compound made of quaternium-18 bentonite that interferes with absorption of the allergen by acting as a physical blocker.²⁴

Treatment

After Toxicodendron dermatitis develops, several treatments are available to help manage symptoms. Calamine lotion can be used to help dry weeping lesions.^25,26 Topical steroids can be used to help control pruritus and alleviate inflammation. High-potency topical corticosteroids such as clobetasol and mid-potency steroids such as triamcinolone can be used. Topical anesthetics (eg, benzocaine, pramoxine, benzyl alcohol) might provide symptomatic relief.^27,28

Oral antihistamines can allow for better sleep by providing sedation but do not target the pruritus of poison ivy dermatitis, which is not histamine mediated.^29,30 Systemic corticosteroids usually are considered in more severe dermatitis—when 20% or more of the body surface area is involved; blistering and itching are severe; or the face, hands, or genitalia are involved.^31,32

Clinical Uses

Therapeutic uses for poison ivy have been explored extensively. In 1892, Dakin³³ reported that ingestion of leaves by Native Americans reduced the incidence and severity of skin lesions after contact with poison ivy. Consumption of poison ivy was further studied by Epstein and colleagues³⁴ in 1974; they concluded that ingestion of a large amount of urushiol over a period of 3 months or longer may help with hyposensitization—but not complete desensitization—to contact with poison ivy. However, the risk for adverse effects is thought to outweigh benefits because ingestion can cause perianal dermatitis, mucocutaneous sequelae, and systemic contact dermatitis.²

Although the use of Toxicodendron plants in modern-day medicine is limited, development of a vaccine (immunotherapy) against Toxicodendron dermatitis offers an exciting opportunity for further research.

Reactions to poison ivy, poison oak, and poison sumac, which affect 10 to 50 million Americans a year,¹ are classified as Toxicodendron dermatitis; 50% to 75% of US adults are clinically sensitive to these plants.² Furthermore, people of all ethnicities, skin types, and ages residing in most US geographical regions are at risk.³ Allergenicity is caused by urushiol, which is found in members of the Anacardiaceae family.⁴ Once absorbed, urushiol causes a type IV hypersensitivity reaction in those who are susceptible.⁵

Cutaneous Manifestations

Toxicodendron dermatitis presents with an acute eczematous eruption characterized by streaks of intensely pruritic and erythematous papules and vesicles (Figure 1). Areas of involvement are characterized by sharp margins that follow the pattern of contact made by the plant’s leaves, berries, stems, and vines.⁶ The fluid content of the vesicles is not antigenic and cannot cause subsequent transmission to oneself or others.³ A person with prior contact to the plant who becomes sensitized develops an eruption 24 to 48 hours after subsequent contact with the plant; peak severity manifests 1 to 14 days later.⁷

Hunt_1.jpg

When left untreated, the eruption can last 3 weeks. If the plant is burned, urushiol can be aerosolized in smoke, causing respiratory tract inflammation and generalized dermatitis, which has been reported among wildland firefighters.² Long-term complications from an outbreak are limited but can include postinflammatory hyperpigmentation and secondary bacterial infection.⁸ Rare reports of nephrotic syndrome also have appeared in the literature.⁹Toxicodendron dermatitis can present distinctively as so-called black dot dermatitis.⁶

Nomenclature

Poison ivy, poison oak, and poison sumac are members of the family Anacardiaceae and genus Toxicodendron,⁶ derived from the Greek words toxikos (poison) and dendron (tree).¹⁰

Distribution

Toxicodendron plants characteristically are found in various regions of the United States. Poison ivy is the most common and is comprised of 2 species: Toxicodendron rydbergii and Toxicodendron radicans. Toxicodendron rydbergii is a nonclimbing dwarf shrub typically found in the northern and western United States. Toxicodendron radicans is a climbing vine found in the eastern United States. Poison oak also is comprised of 2 species—Toxicodendron toxicarium and Toxicodendron diversilobum—and is more common in the western United States. Poison sumac (also known as Toxicodendron vernix) is a small shrub that grows in moist swampy areas. It has a predilection for marshes of the eastern and southeastern United States.^6,11

Identifying Features

Educating patients on how to identify poison ivy can play a key role in avoidance, which is the most important step in preventing Toxicodendron dermatitis. A challenge in identification of poison ivy is the plant’s variable appearance; it grows as a small shrub, low-lying vine, or vine that climbs other trees.

As the vine matures, it develops tiny, rough, “hairy” rootlets—hence the saying, “Hairy vine, no friend of mine!” Rootlets help the plant attach to trees growing near a water source. Vines can reach a diameter of 3 inches. From mature vines, solitary stems extend 1 to 2 inches with 3 characteristic leaves at the terminus (Figure 2), prompting another classic saying, “Leaves of 3, let it be!”¹²

Hunt_2.jpg

Poison oak is characterized by 3 to 5 leaflets. Poison sumac has 7 to 13 pointed, smooth-edged leaves.⁶

Dermatitis-Inducing Plant Parts

The primary allergenic component of Toxicodendron plants is urushiol, a resinous sap found in stems, roots, leaves, and skins of the fruits. These components must be damaged or bruised to release the allergen; slight contact with an uninjured plant part might not lead to harm.^2,13 Some common forms of transmission include skin contact, ingestion, inhalation of smoke from burning plants, and contact with skin through contaminated items, such as clothing, animals, and tools.¹⁴

Allergens

The catecholic ring and aliphatic chain of the urushiol molecule are allergenic.¹⁵ The degree of saturation and length of the side chains vary with different catechols. Urushiol displays cross-reactivity with poison ivy, poison oak, and poison sumac. Urushiol from these plants differs only slightly in structure; therefore, sensitization to one causes sensitization to all. There also is cross-reactivity between different members of the Anacardiaceae family, including Anacardium occidentale (tropical cashew nut), Mangifera indica (tropical mango tree), Ginkgo biloba (ginkgo tree), and Semecarpus anacardium (Indian marking nut tree).¹²

Poison ivy, poison oak, and poison sumac cause allergic contact dermatitis as a type IV hypersensitivity reaction. First, urushiol binds and penetrates the skin, where it is oxidized to quinone intermediates and bound to haptens. Then, the intermediates bind surface proteins on antigen-presenting cells, specifically Langerhans cells in the epidermis and dermis.⁵

Presentation of nonpeptide antigens, such as urushiol, to T cells requires expression of langerin (also known as CD207) and CD1a.¹⁶ Langerin is a C-type lectin that causes formation of Birbeck granules; CD1a is a major histocompatibility complex class I molecule found in Birbeck granules.^5,17 After Langerhans cells internalize and process the urushiol self-hapten neoantigen, it is presented to CD4⁺ T cells.⁶ These cells then expand to form circulating activated T-effector and T-memory lymphocytes.¹⁸

The molecular link that occurs between the hapten and carrier protein determines the response. When linked by an amino nucleophile, selective induction of T-effector cells ensues, resulting in allergic contact dermatitis. When linked by a sulfhydryl bond, selective induction of suppressor cells occurs, resulting in a reduced allergic contact dermatitis response.¹⁹ In the case of activation of T-effector cells, a cell-mediated cytotoxic immune response is generated that destroys epidermal cells and dermal vasculature.² The incidence and intensity of poison ivy sensitivity decline proportionally with age and the absence of continued exposure.²⁰

Preventive Action—Patients should be counseled that if contact between plant and skin occurs, it is important to remove contaminated clothing or objects and wash them with soap to prevent additional exposure.^14,21 Areas of the skin that made contact with the plant should be washed with water as soon as possible; after 30 minutes, urushiol has sufficiently penetrated to cause a reaction.² Forceful unidirectional washing with a damp washcloth and liquid dishwashing soap is recommended.²²

Several barrier creams are commercially available to help prevent absorption or to deactivate the urushiol antigen. These products are used widely by forestry workers and wildland firefighters.²³ One such barrier cream is bentoquatam (sold as various trade names), an organoclay compound made of quaternium-18 bentonite that interferes with absorption of the allergen by acting as a physical blocker.²⁴

Treatment

After Toxicodendron dermatitis develops, several treatments are available to help manage symptoms. Calamine lotion can be used to help dry weeping lesions.^25,26 Topical steroids can be used to help control pruritus and alleviate inflammation. High-potency topical corticosteroids such as clobetasol and mid-potency steroids such as triamcinolone can be used. Topical anesthetics (eg, benzocaine, pramoxine, benzyl alcohol) might provide symptomatic relief.^27,28

Oral antihistamines can allow for better sleep by providing sedation but do not target the pruritus of poison ivy dermatitis, which is not histamine mediated.^29,30 Systemic corticosteroids usually are considered in more severe dermatitis—when 20% or more of the body surface area is involved; blistering and itching are severe; or the face, hands, or genitalia are involved.^31,32

Clinical Uses

Therapeutic uses for poison ivy have been explored extensively. In 1892, Dakin³³ reported that ingestion of leaves by Native Americans reduced the incidence and severity of skin lesions after contact with poison ivy. Consumption of poison ivy was further studied by Epstein and colleagues³⁴ in 1974; they concluded that ingestion of a large amount of urushiol over a period of 3 months or longer may help with hyposensitization—but not complete desensitization—to contact with poison ivy. However, the risk for adverse effects is thought to outweigh benefits because ingestion can cause perianal dermatitis, mucocutaneous sequelae, and systemic contact dermatitis.²

Although the use of Toxicodendron plants in modern-day medicine is limited, development of a vaccine (immunotherapy) against Toxicodendron dermatitis offers an exciting opportunity for further research.

Cutaneous Manifestations

Contact dermatitis is a common problem for individuals who work in the floral industry. Hand dermatitis has been reported in as many as 26% of floral employees.¹Tulipa species have been identified as one of the most common causes of hand dermatitis. Tulipalin A (α-methylene-γ-butyrolactone) is the main sensitizer in tulips (Figure 1) and its precursor tuliposide A also occurs both in tulips and the Peruvian lily (Alstroemeria).

Lee_tulips_1.jpg

In a 1996 study, 18% (9/51) of tulip workers were found to be allergic to tulipalin A.² In a more recent study of 164 tulip workers, 48 (29.3%) had clinical evidence of contact dermatitis and subsequently underwent patch testing; 17 (35.4%) showed a positive reaction to either tulipalin A or to tulip-bulb extract.³ Itching was the most common symptom (39 workers [81.3%]) and hand eczema at the tip of the thumb and index finger was the most common finding. In 9 (18.8%) workers, eczema had spread to other body parts including the forearm, face, legs, and abdomen.³

Peruvian lily is widely used in floral arrangements and has become a leading cause of hand dermatitis in florists (Figure 2). Large amounts of free tulipalin A are present in bulb scales of tulips, along with a small amount of tuliposide A. In young developing shoots, the situation is reversed: Both compounds are found in all parts of the plant to some degree, though tulipalin A is the major allergen, and more mature parts of the plant and bulb are most allergenic.

CT110003145_Fig2_AB.jpg

Cultural Considerations

In traditional Kurdish cuisine, raw herbs are part of snacking or are served as a side dish (sawza). Snacks often are consumed raw on the spot. Tulipa montana, Tulipa armena, and possibly other Tulipa species are consumed as a snack.⁴ Traditionally, Tulipa systola is consumed by the Kurds as an anti-inflammatory medicine and for pain relief. It also has been proposed that T systola has antioxidant properties.⁵ Cooked tulip also has been consumed in time of famine in Europe, though none of these dietary practices are recommended.⁴

Clinical Presentation

“Tulip fingers” describes the most common presentation of contact dermatitis caused by tulip bulbs. Erythematous scaling plaques are seen in the periungual skin and first and second fingertips of the dominant hand. Other manifestations include diffuse dry dermatitis of the hand; paronychia; pulpitis; and secondary spread to the face, neck, arms, and genitalia, with eczematous papules and plaques.⁶ Clinical signs include erythema, vesicles, hyperkeratosis, and exfoliation of the fingertips. The allergen also can cause airborne contact dermatitis and manifest as conjunctivitis, rhinitis, and asthma.² A considerable number of tulip workers develop paresthesia and tenderness in the fingertips within several hours after working with tulip bulbs, known as “tulip fire.”⁷

Plant Facts

There are approximately 250 genera of bulbous plants. Tulips are members of the genus Tulipa and family Liliaceae. Tulips often are thought of as native to southwest central Asia and Turkey⁸; however, Tulipa sylvestris is native to Portugal, Spain, and North Africa.

Etymology and Symbolism—The word tulip is derived from the Turkish word türbent meaning a turban, possibly because the flower is compared to turbans worn by men of the Ottoman Empire in the 16th century. In Turkish culture, the tulip is a symbol of paradise on earth and can have divine status. In the Netherlands, on the other hand, the tulip represents the briefness of life.

History—By 1562, tulip bulbs had already been introduced to Holland by merchants. However, the first shipment of tulip bulbs was mistaken by the Dutch for onions and were either roasted over a fire or perished when planted in gardens with vegetables. Carolus Clusius—botanist, director of the imperial medical garden in Vienna and recipient of many plants through diplomatic channels—was particularly fond of flower bulbs and contributed to the popularity of the tulip in Europe by sending bulbs and seeds to other European countries.

In the early 17th century, the tulip craze began in France, fueled by a viral disease of tulips that produced variegated color patterns on the petals; entire properties were sold in exchange for a single tulip bulb. The tulip craze drifted from France to Holland in 1634 for 3 years before the tulip market collapsed.

More recently, in 2003 investors started a multimillion-euro tulip fund in the Netherlands to develop new varieties of tulip. Tulip bulbs were used to create money with high percentages over the selling price. With exorbitant pricing and ever-changing ownership of bulbs—bulbs were bought and sold as many as 10 times—the tulip fund collapsed 1 year later and investors lost their money. Bulb speculators then took their profit abroad. In 2006, bulb owners were charged with fraud; the tulip craze often is cited as one of the early major stock market collapses.

Tulips continue to grow in popularity. Today, nearly 6000 cultivars are registered, with 40 new cultivars registered every 5 years.⁹

Identifying Features

At the base of the erect tulip plant is a cluster of 2 or 3 thick bluish-green leaves. Three petals and 3 sepals make up the solitary bell-shaped flower. Many tulips can propagate only by means of their scaly bulbs. The flowers arise from the tips of stems in different solid colors, except true blue—from pure white to all shades of yellow, red, and a deep purple that is almost black. Solid-color tulips are called “self-colored.” So-called broken tulips are individual flowers with multiple colors, a condition caused by a viral disease transmitted by aphids.¹⁰

Tulip Allergen

Tuliposide A is found in many species of the genera Tulipa, Alstroemeria, and Erythronium.⁶ So far, 7 analogs have been identified: 1-tuliposide A and B; 6-tuliposide A and B; and tuliposides D, E, and F. 6-Tuliposide A and B are the principal tuliposides found in tulip cultivars.¹¹ With trauma and maturation, tuliposides A and B are hydrolyzed to tulipalin A and tulipalin B, respectively.

Tulipalin A and tulipalin B have antimicrobial properties against bacteria and fungi; tulipalin A is mostly an antifungal agent, and tulipalin B has mostly bacteriostatic characteristics.¹² The highest concentration of tulipalin A is found in the outer layer of the bulb, followed by (in descending order) the stem, leaves, and petals.¹³

The prevalence of tulipalin A allergy led the German Federal Institute for Risk Assessment to assign tuliposide A and tulipalin A to category B, which is a “solid-based indication for contact allergenic effects”; both chemicals also are considered skin sensitizers, defined by the Globally Harmonized System of Classification and Labelling of Chemicals of the United Nations as a substance that will induce an allergic response following skin contact.¹⁴ Patients who are allergic to tulips have cross-sensitivity to Alstroemeria because tuliposide A and its metabolites are found in both plants.¹⁵

Symptoms of an allergic response to tulipalin A can be immediate or delayed.¹⁴ The most common allergic contact dermatitis caused by tulip bulbs is type IV hypersensitivity, though type I reactions can occur. Symptoms of a type I reaction including contact urticaria, rhinitis, hoarseness, and dyspnea have been reported.¹⁴

The variety of tulip handled also contributes to the severity of dermatitis. Handling bulbs of Rose Copeland variety tulips and cutting the flowers of Preludium tulips have been associated with more severe allergic dermatitis presentations, whereas the Red Emperor tulip was found to have less tuliposide A and thus provoke a weaker patch-test reaction.⁷

A Word About Garlic—Garlic is in the subfamily Allioideae (formerly Alliaceae) taxonomically related to the tulip family (Liliaceae). Garlic also can cause hand dermatitis in cooks, with a similar clinical appearance as tulip fingers. Gas chromatography has shown that garlic contains predominantly tuliposide B, which has been found to be much less allergenic than tuliposide A.^7,16

Prevention of Tulipa Dermatitis

Tuliposide A and its metabolites can be found in storehouses and trucks used to transport tulips, in clothing, and in any other place where dust containing the allergen has settled. The best prevention against contact dermatitis is to avoid the inciting plants. Gloves may prevent contact dermatitis due to tuliposide A, which penetrates vinyl but not nitrile gloves. Barrier creams have been proposed, but data are scant.¹

Cutaneous Manifestations

Contact dermatitis is a common problem for individuals who work in the floral industry. Hand dermatitis has been reported in as many as 26% of floral employees.¹Tulipa species have been identified as one of the most common causes of hand dermatitis. Tulipalin A (α-methylene-γ-butyrolactone) is the main sensitizer in tulips (Figure 1) and its precursor tuliposide A also occurs both in tulips and the Peruvian lily (Alstroemeria).

Lee_tulips_1.jpg

In a 1996 study, 18% (9/51) of tulip workers were found to be allergic to tulipalin A.² In a more recent study of 164 tulip workers, 48 (29.3%) had clinical evidence of contact dermatitis and subsequently underwent patch testing; 17 (35.4%) showed a positive reaction to either tulipalin A or to tulip-bulb extract.³ Itching was the most common symptom (39 workers [81.3%]) and hand eczema at the tip of the thumb and index finger was the most common finding. In 9 (18.8%) workers, eczema had spread to other body parts including the forearm, face, legs, and abdomen.³

Peruvian lily is widely used in floral arrangements and has become a leading cause of hand dermatitis in florists (Figure 2). Large amounts of free tulipalin A are present in bulb scales of tulips, along with a small amount of tuliposide A. In young developing shoots, the situation is reversed: Both compounds are found in all parts of the plant to some degree, though tulipalin A is the major allergen, and more mature parts of the plant and bulb are most allergenic.

CT110003145_Fig2_AB.jpg

Cultural Considerations

In traditional Kurdish cuisine, raw herbs are part of snacking or are served as a side dish (sawza). Snacks often are consumed raw on the spot. Tulipa montana, Tulipa armena, and possibly other Tulipa species are consumed as a snack.⁴ Traditionally, Tulipa systola is consumed by the Kurds as an anti-inflammatory medicine and for pain relief. It also has been proposed that T systola has antioxidant properties.⁵ Cooked tulip also has been consumed in time of famine in Europe, though none of these dietary practices are recommended.⁴

Clinical Presentation

“Tulip fingers” describes the most common presentation of contact dermatitis caused by tulip bulbs. Erythematous scaling plaques are seen in the periungual skin and first and second fingertips of the dominant hand. Other manifestations include diffuse dry dermatitis of the hand; paronychia; pulpitis; and secondary spread to the face, neck, arms, and genitalia, with eczematous papules and plaques.⁶ Clinical signs include erythema, vesicles, hyperkeratosis, and exfoliation of the fingertips. The allergen also can cause airborne contact dermatitis and manifest as conjunctivitis, rhinitis, and asthma.² A considerable number of tulip workers develop paresthesia and tenderness in the fingertips within several hours after working with tulip bulbs, known as “tulip fire.”⁷

Plant Facts

There are approximately 250 genera of bulbous plants. Tulips are members of the genus Tulipa and family Liliaceae. Tulips often are thought of as native to southwest central Asia and Turkey⁸; however, Tulipa sylvestris is native to Portugal, Spain, and North Africa.

Etymology and Symbolism—The word tulip is derived from the Turkish word türbent meaning a turban, possibly because the flower is compared to turbans worn by men of the Ottoman Empire in the 16th century. In Turkish culture, the tulip is a symbol of paradise on earth and can have divine status. In the Netherlands, on the other hand, the tulip represents the briefness of life.

History—By 1562, tulip bulbs had already been introduced to Holland by merchants. However, the first shipment of tulip bulbs was mistaken by the Dutch for onions and were either roasted over a fire or perished when planted in gardens with vegetables. Carolus Clusius—botanist, director of the imperial medical garden in Vienna and recipient of many plants through diplomatic channels—was particularly fond of flower bulbs and contributed to the popularity of the tulip in Europe by sending bulbs and seeds to other European countries.

In the early 17th century, the tulip craze began in France, fueled by a viral disease of tulips that produced variegated color patterns on the petals; entire properties were sold in exchange for a single tulip bulb. The tulip craze drifted from France to Holland in 1634 for 3 years before the tulip market collapsed.

More recently, in 2003 investors started a multimillion-euro tulip fund in the Netherlands to develop new varieties of tulip. Tulip bulbs were used to create money with high percentages over the selling price. With exorbitant pricing and ever-changing ownership of bulbs—bulbs were bought and sold as many as 10 times—the tulip fund collapsed 1 year later and investors lost their money. Bulb speculators then took their profit abroad. In 2006, bulb owners were charged with fraud; the tulip craze often is cited as one of the early major stock market collapses.

Tulips continue to grow in popularity. Today, nearly 6000 cultivars are registered, with 40 new cultivars registered every 5 years.⁹

Identifying Features

At the base of the erect tulip plant is a cluster of 2 or 3 thick bluish-green leaves. Three petals and 3 sepals make up the solitary bell-shaped flower. Many tulips can propagate only by means of their scaly bulbs. The flowers arise from the tips of stems in different solid colors, except true blue—from pure white to all shades of yellow, red, and a deep purple that is almost black. Solid-color tulips are called “self-colored.” So-called broken tulips are individual flowers with multiple colors, a condition caused by a viral disease transmitted by aphids.¹⁰

Tulip Allergen

Tuliposide A is found in many species of the genera Tulipa, Alstroemeria, and Erythronium.⁶ So far, 7 analogs have been identified: 1-tuliposide A and B; 6-tuliposide A and B; and tuliposides D, E, and F. 6-Tuliposide A and B are the principal tuliposides found in tulip cultivars.¹¹ With trauma and maturation, tuliposides A and B are hydrolyzed to tulipalin A and tulipalin B, respectively.

Tulipalin A and tulipalin B have antimicrobial properties against bacteria and fungi; tulipalin A is mostly an antifungal agent, and tulipalin B has mostly bacteriostatic characteristics.¹² The highest concentration of tulipalin A is found in the outer layer of the bulb, followed by (in descending order) the stem, leaves, and petals.¹³

The prevalence of tulipalin A allergy led the German Federal Institute for Risk Assessment to assign tuliposide A and tulipalin A to category B, which is a “solid-based indication for contact allergenic effects”; both chemicals also are considered skin sensitizers, defined by the Globally Harmonized System of Classification and Labelling of Chemicals of the United Nations as a substance that will induce an allergic response following skin contact.¹⁴ Patients who are allergic to tulips have cross-sensitivity to Alstroemeria because tuliposide A and its metabolites are found in both plants.¹⁵

Symptoms of an allergic response to tulipalin A can be immediate or delayed.¹⁴ The most common allergic contact dermatitis caused by tulip bulbs is type IV hypersensitivity, though type I reactions can occur. Symptoms of a type I reaction including contact urticaria, rhinitis, hoarseness, and dyspnea have been reported.¹⁴

The variety of tulip handled also contributes to the severity of dermatitis. Handling bulbs of Rose Copeland variety tulips and cutting the flowers of Preludium tulips have been associated with more severe allergic dermatitis presentations, whereas the Red Emperor tulip was found to have less tuliposide A and thus provoke a weaker patch-test reaction.⁷

A Word About Garlic—Garlic is in the subfamily Allioideae (formerly Alliaceae) taxonomically related to the tulip family (Liliaceae). Garlic also can cause hand dermatitis in cooks, with a similar clinical appearance as tulip fingers. Gas chromatography has shown that garlic contains predominantly tuliposide B, which has been found to be much less allergenic than tuliposide A.^7,16

Prevention of Tulipa Dermatitis

Tuliposide A and its metabolites can be found in storehouses and trucks used to transport tulips, in clothing, and in any other place where dust containing the allergen has settled. The best prevention against contact dermatitis is to avoid the inciting plants. Gloves may prevent contact dermatitis due to tuliposide A, which penetrates vinyl but not nitrile gloves. Barrier creams have been proposed, but data are scant.¹

Cutaneous Manifestations

Contact dermatitis is a common problem for individuals who work in the floral industry. Hand dermatitis has been reported in as many as 26% of floral employees.¹Tulipa species have been identified as one of the most common causes of hand dermatitis. Tulipalin A (α-methylene-γ-butyrolactone) is the main sensitizer in tulips (Figure 1) and its precursor tuliposide A also occurs both in tulips and the Peruvian lily (Alstroemeria).

Lee_tulips_1.jpg

In a 1996 study, 18% (9/51) of tulip workers were found to be allergic to tulipalin A.² In a more recent study of 164 tulip workers, 48 (29.3%) had clinical evidence of contact dermatitis and subsequently underwent patch testing; 17 (35.4%) showed a positive reaction to either tulipalin A or to tulip-bulb extract.³ Itching was the most common symptom (39 workers [81.3%]) and hand eczema at the tip of the thumb and index finger was the most common finding. In 9 (18.8%) workers, eczema had spread to other body parts including the forearm, face, legs, and abdomen.³

Peruvian lily is widely used in floral arrangements and has become a leading cause of hand dermatitis in florists (Figure 2). Large amounts of free tulipalin A are present in bulb scales of tulips, along with a small amount of tuliposide A. In young developing shoots, the situation is reversed: Both compounds are found in all parts of the plant to some degree, though tulipalin A is the major allergen, and more mature parts of the plant and bulb are most allergenic.

CT110003145_Fig2_AB.jpg

Cultural Considerations

In traditional Kurdish cuisine, raw herbs are part of snacking or are served as a side dish (sawza). Snacks often are consumed raw on the spot. Tulipa montana, Tulipa armena, and possibly other Tulipa species are consumed as a snack.⁴ Traditionally, Tulipa systola is consumed by the Kurds as an anti-inflammatory medicine and for pain relief. It also has been proposed that T systola has antioxidant properties.⁵ Cooked tulip also has been consumed in time of famine in Europe, though none of these dietary practices are recommended.⁴

Clinical Presentation

“Tulip fingers” describes the most common presentation of contact dermatitis caused by tulip bulbs. Erythematous scaling plaques are seen in the periungual skin and first and second fingertips of the dominant hand. Other manifestations include diffuse dry dermatitis of the hand; paronychia; pulpitis; and secondary spread to the face, neck, arms, and genitalia, with eczematous papules and plaques.⁶ Clinical signs include erythema, vesicles, hyperkeratosis, and exfoliation of the fingertips. The allergen also can cause airborne contact dermatitis and manifest as conjunctivitis, rhinitis, and asthma.² A considerable number of tulip workers develop paresthesia and tenderness in the fingertips within several hours after working with tulip bulbs, known as “tulip fire.”⁷

Plant Facts

There are approximately 250 genera of bulbous plants. Tulips are members of the genus Tulipa and family Liliaceae. Tulips often are thought of as native to southwest central Asia and Turkey⁸; however, Tulipa sylvestris is native to Portugal, Spain, and North Africa.

Etymology and Symbolism—The word tulip is derived from the Turkish word türbent meaning a turban, possibly because the flower is compared to turbans worn by men of the Ottoman Empire in the 16th century. In Turkish culture, the tulip is a symbol of paradise on earth and can have divine status. In the Netherlands, on the other hand, the tulip represents the briefness of life.

History—By 1562, tulip bulbs had already been introduced to Holland by merchants. However, the first shipment of tulip bulbs was mistaken by the Dutch for onions and were either roasted over a fire or perished when planted in gardens with vegetables. Carolus Clusius—botanist, director of the imperial medical garden in Vienna and recipient of many plants through diplomatic channels—was particularly fond of flower bulbs and contributed to the popularity of the tulip in Europe by sending bulbs and seeds to other European countries.

In the early 17th century, the tulip craze began in France, fueled by a viral disease of tulips that produced variegated color patterns on the petals; entire properties were sold in exchange for a single tulip bulb. The tulip craze drifted from France to Holland in 1634 for 3 years before the tulip market collapsed.

More recently, in 2003 investors started a multimillion-euro tulip fund in the Netherlands to develop new varieties of tulip. Tulip bulbs were used to create money with high percentages over the selling price. With exorbitant pricing and ever-changing ownership of bulbs—bulbs were bought and sold as many as 10 times—the tulip fund collapsed 1 year later and investors lost their money. Bulb speculators then took their profit abroad. In 2006, bulb owners were charged with fraud; the tulip craze often is cited as one of the early major stock market collapses.

Tulips continue to grow in popularity. Today, nearly 6000 cultivars are registered, with 40 new cultivars registered every 5 years.⁹

Identifying Features

At the base of the erect tulip plant is a cluster of 2 or 3 thick bluish-green leaves. Three petals and 3 sepals make up the solitary bell-shaped flower. Many tulips can propagate only by means of their scaly bulbs. The flowers arise from the tips of stems in different solid colors, except true blue—from pure white to all shades of yellow, red, and a deep purple that is almost black. Solid-color tulips are called “self-colored.” So-called broken tulips are individual flowers with multiple colors, a condition caused by a viral disease transmitted by aphids.¹⁰

Tulip Allergen

Tuliposide A is found in many species of the genera Tulipa, Alstroemeria, and Erythronium.⁶ So far, 7 analogs have been identified: 1-tuliposide A and B; 6-tuliposide A and B; and tuliposides D, E, and F. 6-Tuliposide A and B are the principal tuliposides found in tulip cultivars.¹¹ With trauma and maturation, tuliposides A and B are hydrolyzed to tulipalin A and tulipalin B, respectively.

Tulipalin A and tulipalin B have antimicrobial properties against bacteria and fungi; tulipalin A is mostly an antifungal agent, and tulipalin B has mostly bacteriostatic characteristics.¹² The highest concentration of tulipalin A is found in the outer layer of the bulb, followed by (in descending order) the stem, leaves, and petals.¹³

The prevalence of tulipalin A allergy led the German Federal Institute for Risk Assessment to assign tuliposide A and tulipalin A to category B, which is a “solid-based indication for contact allergenic effects”; both chemicals also are considered skin sensitizers, defined by the Globally Harmonized System of Classification and Labelling of Chemicals of the United Nations as a substance that will induce an allergic response following skin contact.¹⁴ Patients who are allergic to tulips have cross-sensitivity to Alstroemeria because tuliposide A and its metabolites are found in both plants.¹⁵

Symptoms of an allergic response to tulipalin A can be immediate or delayed.¹⁴ The most common allergic contact dermatitis caused by tulip bulbs is type IV hypersensitivity, though type I reactions can occur. Symptoms of a type I reaction including contact urticaria, rhinitis, hoarseness, and dyspnea have been reported.¹⁴

The variety of tulip handled also contributes to the severity of dermatitis. Handling bulbs of Rose Copeland variety tulips and cutting the flowers of Preludium tulips have been associated with more severe allergic dermatitis presentations, whereas the Red Emperor tulip was found to have less tuliposide A and thus provoke a weaker patch-test reaction.⁷

A Word About Garlic—Garlic is in the subfamily Allioideae (formerly Alliaceae) taxonomically related to the tulip family (Liliaceae). Garlic also can cause hand dermatitis in cooks, with a similar clinical appearance as tulip fingers. Gas chromatography has shown that garlic contains predominantly tuliposide B, which has been found to be much less allergenic than tuliposide A.^7,16

Prevention of Tulipa Dermatitis

Tuliposide A and its metabolites can be found in storehouses and trucks used to transport tulips, in clothing, and in any other place where dust containing the allergen has settled. The best prevention against contact dermatitis is to avoid the inciting plants. Gloves may prevent contact dermatitis due to tuliposide A, which penetrates vinyl but not nitrile gloves. Barrier creams have been proposed, but data are scant.¹

An ancient tree of the Ginkgoaceae family, Ginkgo biloba is known as a living fossil because its genome has been identified in fossils older than 200 million years.¹ An individual tree can live longer than 1000 years. Originating in China, G biloba (here, “ginkgo”) is cultivated worldwide for its attractive foliage (Figure 1). Ginkgo extract has long been used in traditional Chinese medicine; however, contact with the plant proper can provoke allergic contact dermatitis.

Barker_1.JPG

Dermatitis-Inducing Components

The allergenic component of the ginkgo tree is ginkgolic acid, which is structurally similar to urushiol and anacardic acid.^2,3 This compound can cause a cross-reaction in a person previously sensitized by contact with other plants. Urushiol is found in poison ivy(Toxicodendron radicans); anacardic acid is found in the cashew tree (Anacardium occidentale). Both plants belong to the family Anacardiaceae, commonly known as the cashew family.

Members of Anacardiaceae are the most common causes of plant-induced allergic contact dermatitis and include the cashew tree, mango tree, poison ivy, poison oak, and poison sumac. These plants can cross-react to cause contact dermatitis (Table).³ Patch tests have revealed that some individuals who are sensitive to components of the ginkgo tree also demonstrate sensitivity to poison ivy and poison sumac^4,5; countering this finding, Lepoittevin and colleagues⁶ demonstrated in animal studies that there was no cross-reactivity between ginkgo and urushiol, suggesting that patients with a reported cross-reaction might truly have been previously sensitized to both plants. In general, patients who have a history of a reaction to any Anacardiaceae plant should take precautions when handling them.

CT110001030_Table.JPG

Therapeutic Benefit of Ginkgo

Ginkgo extract is sold as the herbal supplement EGB761, which acts as an antioxidant.⁷ In France, Germany, and China, it is a commonly prescribed herbal medicine.⁸ It is purported to support memory and attention; studies have shown improvement in cognition and in involvement with activities of daily living for patients with dementia.^9,10 Ginkgo extract might lessen peripheral vascular disease and cerebral circulatory disease, having been shown in vitro and in animal models to prevent platelet aggregation induced by platelet-activating factor and to stimulate vasodilation by increasing production of nitric oxide.^11,12

Furthermore, purified ginkgo extract might have beneficial effects on skin. A study in rats showed that when intraperitoneal ginkgo extract was given prior to radiation therapy, 100% of rats receiving placebo developed radiation dermatitis vs 13% of those that received ginkgo extract (P<.0001). An excisional skin biopsy showed a decrease in markers of oxidative stress in rats that received ginkgo extract prior to radiation.⁷

A randomized, double-blind clinical trial showed a significant reduction in disease progression in vitiligo patients assigned to receive ginkgo extract orally compared to placebo (P=.006).¹³ Research for many possible uses of ginkgo extract is ongoing.

Cutaneous Manifestations

Contact with the fruit of the ginkgo tree can induce allergic contact dermatitis,¹⁴ most often as erythematous papules, vesicles, and in some cases edema.^5,15

Exposures While Picking Berries—In 1939, Bolus¹⁵ reported the case of a patient who presented with edema, erythema, and vesicular lesions involving the hands and face after picking berries from a ginkgo tree. Later, patch testing on this patient, using ginkgo fruit, resulted in burning and stinging that necessitated removal of the patch, suggesting an irritant reaction. This was followed by a vesicular reaction that then developed within 24 hours, which was more consistent with allergy. Similarly, in 1988, a case series of contact dermatitis was reported in 3 patients after gathering ginkgo fruit.⁵

Incidental Exposure While Walking—In 1965, dermatitis broke out in 35 high school students, mainly affecting exposed portions of the leg, after ginkgo fruit fell and its pulp was exposed on a path at their school.⁴ Subsequently, patch testing was performed on 29 volunteers—some who had been exposed to ginkgo on that path, others without prior exposure. It was established that testing with ginkgo pulp directly caused an irritant reaction in all students, regardless of prior ginkgo exposure, but all prior ginkgo-exposed students in this study reacted positively to an acetone extract of ginkgo pulp and either poison ivy extract or pentadecylcatechol.⁴

Systemic Contact After Eating Fruit—An illustrative case of dermatitis, stomatitis, and proctitis was reported in a man with history of poison oak contact dermatitis who had eaten fruit from a ginkgo tree, suggesting systemic contact dermatitis. Weeks after resolution of symptoms, he reacted positively to ginkgo fruit and poison ivy extracts on patch testing.¹⁶

Ginkgo dermatitis tends to resolve upon removal of the inciting agent and application of a topical steroid.^8,17 Although many reported cases involve the fruit, allergic contact dermatitis can result from exposure to any part of the plant. In a reported case, a woman developed airborne contact dermatitis from working with sarcotesta of the ginkgo plant.¹⁸ Despite wearing rubber gloves, she broke out 1 week after exposure with erythema on the face and arms and severe facial edema.

Ginkgo leaves also can cause allergic contact dermatitis.¹⁹ Precautions should be taken when handling any component of the ginkgo tree.

Oral ginkgo supplementation has been implicated in a variety of other cutaneous reactions—from benign to life-threatening. When the ginkgo allergen concentration is too high within the supplement, as has been noted in some formulations, patients have presented with a diffuse morbilliform eruption within 1 or 2 weeks after taking ginkgo.²⁰ One patient—who was not taking any other medication—experienced an episode of acute generalized exanthematous pustulosis 48 hours after taking ginkgo.²¹ Ingestion of ginkgo extract also has been associated with Stevens-Johnson syndrome.^22-24

Other Adverse Reactions

The adverse effects of ginkgo supplement vary widely. In addition to dermatitis, ginkgo supplement can cause headaches, palpitations, tachycardia, vasculitis, nausea, and other symptoms.¹⁴

Metabolic Disturbance—One patient taking ginkgo who died after a seizure was found to have subtherapeutic levels of valproate and phenytoin,²⁵ which could be due to ginkgo’s effect on cytochrome p450 enzyme CYP2C19.²⁶ Ginkgo interactions with many cytochrome enzymes have been studied for potential drug interactions. Any other direct effects remain variable and controversial.^27,28

Hemorrhage—Another serious effect associated with taking ginkgo supplements is hemorrhage, often in conjunction with warfarin¹⁴; however, a meta-analysis indicated that ginkgo generally does not increase the risk of bleeding.²⁹ Other studies have shown that taking ginkgo with warfarin showed no difference in clotting status, and ginkgo with aspirin resulted in no clinically significant difference in bruising, bleeding, or platelet function in an analysis over a period of 1 month.^30,31 These findings notwithstanding, pregnant women, surgical patients, and those taking a blood thinner are advised as a general precaution not to take ginkgo extract.

Carcinogenesis—Ginkgo extract has antioxidant properties, but there is evidence that it might act as a carcinogen. An animal study reported by the US National Toxicology Program found that ginkgo induced mutagenic activity in the liver, thyroid, and nose of mice and rats. Over time, rodent liver underwent changes consistent with hepatic enzyme induction.³² More research is needed to clarify the role of ginkgo in this process.

Toxicity by Ingestion—Ginkgo seeds can cause food poisoning due to the compound 4’-O-methylpyridoxine (also known as ginkgotoxin).³³ Because methylpyridoxine can cause depletion of pyridoxal phosphate (a form of vitamin B₆ necessary for the synthesis of γ-aminobutyric acid), overconsumption of ginkgo seeds, even when fully cooked, might result in convulsions and even death.³³

Nomenclature and Distribution of Plants

Gingko biloba belongs to the Ginkgoaceae family (class Ginkgophytes). The tree originated in China but might no longer exist in a truly wild form. It is grown worldwide for its beauty and longevity. The female ginkgo tree is a gymnosperm, producing fruit with seeds that are not coated by an ovary wall¹⁵; male (nonfruiting) trees are preferentially planted because the fruit is surrounded by a pulp that, when dropped, emits a sour smell described variously as rancid butter, vomit, or excrement.⁵

Identifying Features and Plant Facts

The deciduous ginkgo tree has unique fan-shaped leaves and is cultivated for its beauty and resistance to disease (Figure 2).^4,34 It is nicknamed the maidenhair tree because the leaves are similar to the pinnae of the maidenhair fern.³⁴ Because G biloba is resistant to pollution, it often is planted along city streets.¹⁷ The leaf—5- to 8-cm wide and a symbol of the city of Tokyo, Japan³⁴—grows in clusters (Figure 3)⁵ and is green but turns yellow before it falls in autumn.³⁴ Leaf veins branch out into the blade without anastomosing.³⁴

Barker_2.JPG

Male flowers grow in a catkinlike pattern; female flowers grow on long stems.⁵ The fruit is small, dark, and shriveled, with a hint of silver⁴; it typically is 2 to 2.5 cm in diameter and contains the ginkgo nut or seed. The kernel of the ginkgo nut is edible when roasted and is used in traditional Chinese and Japanese cuisine as a dish served on special occasions in autumn.³³

Barker_3.JPG

Final Thoughts

Given that G biloba is a beautiful, commonly planted ornamental tree, gardeners and landscapers should be aware of the risk for allergic contact dermatitis and use proper protection. Dermatologists should be aware of its cross-reactivity with other common plants such as poison ivy and poison oak to help patients identify the cause of their reactions and avoid the inciting agent. Because ginkgo extract also can cause a cutaneous reaction or interact with other medications, providers should remember to take a thorough medication history that includes herbal medicines and supplements.

An ancient tree of the Ginkgoaceae family, Ginkgo biloba is known as a living fossil because its genome has been identified in fossils older than 200 million years.¹ An individual tree can live longer than 1000 years. Originating in China, G biloba (here, “ginkgo”) is cultivated worldwide for its attractive foliage (Figure 1). Ginkgo extract has long been used in traditional Chinese medicine; however, contact with the plant proper can provoke allergic contact dermatitis.

Barker_1.JPG

Dermatitis-Inducing Components

The allergenic component of the ginkgo tree is ginkgolic acid, which is structurally similar to urushiol and anacardic acid.^2,3 This compound can cause a cross-reaction in a person previously sensitized by contact with other plants. Urushiol is found in poison ivy(Toxicodendron radicans); anacardic acid is found in the cashew tree (Anacardium occidentale). Both plants belong to the family Anacardiaceae, commonly known as the cashew family.

Members of Anacardiaceae are the most common causes of plant-induced allergic contact dermatitis and include the cashew tree, mango tree, poison ivy, poison oak, and poison sumac. These plants can cross-react to cause contact dermatitis (Table).³ Patch tests have revealed that some individuals who are sensitive to components of the ginkgo tree also demonstrate sensitivity to poison ivy and poison sumac^4,5; countering this finding, Lepoittevin and colleagues⁶ demonstrated in animal studies that there was no cross-reactivity between ginkgo and urushiol, suggesting that patients with a reported cross-reaction might truly have been previously sensitized to both plants. In general, patients who have a history of a reaction to any Anacardiaceae plant should take precautions when handling them.

CT110001030_Table.JPG

Therapeutic Benefit of Ginkgo

Ginkgo extract is sold as the herbal supplement EGB761, which acts as an antioxidant.⁷ In France, Germany, and China, it is a commonly prescribed herbal medicine.⁸ It is purported to support memory and attention; studies have shown improvement in cognition and in involvement with activities of daily living for patients with dementia.^9,10 Ginkgo extract might lessen peripheral vascular disease and cerebral circulatory disease, having been shown in vitro and in animal models to prevent platelet aggregation induced by platelet-activating factor and to stimulate vasodilation by increasing production of nitric oxide.^11,12

Furthermore, purified ginkgo extract might have beneficial effects on skin. A study in rats showed that when intraperitoneal ginkgo extract was given prior to radiation therapy, 100% of rats receiving placebo developed radiation dermatitis vs 13% of those that received ginkgo extract (P<.0001). An excisional skin biopsy showed a decrease in markers of oxidative stress in rats that received ginkgo extract prior to radiation.⁷

A randomized, double-blind clinical trial showed a significant reduction in disease progression in vitiligo patients assigned to receive ginkgo extract orally compared to placebo (P=.006).¹³ Research for many possible uses of ginkgo extract is ongoing.

Cutaneous Manifestations

Contact with the fruit of the ginkgo tree can induce allergic contact dermatitis,¹⁴ most often as erythematous papules, vesicles, and in some cases edema.^5,15

Exposures While Picking Berries—In 1939, Bolus¹⁵ reported the case of a patient who presented with edema, erythema, and vesicular lesions involving the hands and face after picking berries from a ginkgo tree. Later, patch testing on this patient, using ginkgo fruit, resulted in burning and stinging that necessitated removal of the patch, suggesting an irritant reaction. This was followed by a vesicular reaction that then developed within 24 hours, which was more consistent with allergy. Similarly, in 1988, a case series of contact dermatitis was reported in 3 patients after gathering ginkgo fruit.⁵

Incidental Exposure While Walking—In 1965, dermatitis broke out in 35 high school students, mainly affecting exposed portions of the leg, after ginkgo fruit fell and its pulp was exposed on a path at their school.⁴ Subsequently, patch testing was performed on 29 volunteers—some who had been exposed to ginkgo on that path, others without prior exposure. It was established that testing with ginkgo pulp directly caused an irritant reaction in all students, regardless of prior ginkgo exposure, but all prior ginkgo-exposed students in this study reacted positively to an acetone extract of ginkgo pulp and either poison ivy extract or pentadecylcatechol.⁴

Systemic Contact After Eating Fruit—An illustrative case of dermatitis, stomatitis, and proctitis was reported in a man with history of poison oak contact dermatitis who had eaten fruit from a ginkgo tree, suggesting systemic contact dermatitis. Weeks after resolution of symptoms, he reacted positively to ginkgo fruit and poison ivy extracts on patch testing.¹⁶

Ginkgo dermatitis tends to resolve upon removal of the inciting agent and application of a topical steroid.^8,17 Although many reported cases involve the fruit, allergic contact dermatitis can result from exposure to any part of the plant. In a reported case, a woman developed airborne contact dermatitis from working with sarcotesta of the ginkgo plant.¹⁸ Despite wearing rubber gloves, she broke out 1 week after exposure with erythema on the face and arms and severe facial edema.

Ginkgo leaves also can cause allergic contact dermatitis.¹⁹ Precautions should be taken when handling any component of the ginkgo tree.

Oral ginkgo supplementation has been implicated in a variety of other cutaneous reactions—from benign to life-threatening. When the ginkgo allergen concentration is too high within the supplement, as has been noted in some formulations, patients have presented with a diffuse morbilliform eruption within 1 or 2 weeks after taking ginkgo.²⁰ One patient—who was not taking any other medication—experienced an episode of acute generalized exanthematous pustulosis 48 hours after taking ginkgo.²¹ Ingestion of ginkgo extract also has been associated with Stevens-Johnson syndrome.^22-24

Other Adverse Reactions

The adverse effects of ginkgo supplement vary widely. In addition to dermatitis, ginkgo supplement can cause headaches, palpitations, tachycardia, vasculitis, nausea, and other symptoms.¹⁴

Metabolic Disturbance—One patient taking ginkgo who died after a seizure was found to have subtherapeutic levels of valproate and phenytoin,²⁵ which could be due to ginkgo’s effect on cytochrome p450 enzyme CYP2C19.²⁶ Ginkgo interactions with many cytochrome enzymes have been studied for potential drug interactions. Any other direct effects remain variable and controversial.^27,28

Hemorrhage—Another serious effect associated with taking ginkgo supplements is hemorrhage, often in conjunction with warfarin¹⁴; however, a meta-analysis indicated that ginkgo generally does not increase the risk of bleeding.²⁹ Other studies have shown that taking ginkgo with warfarin showed no difference in clotting status, and ginkgo with aspirin resulted in no clinically significant difference in bruising, bleeding, or platelet function in an analysis over a period of 1 month.^30,31 These findings notwithstanding, pregnant women, surgical patients, and those taking a blood thinner are advised as a general precaution not to take ginkgo extract.

Carcinogenesis—Ginkgo extract has antioxidant properties, but there is evidence that it might act as a carcinogen. An animal study reported by the US National Toxicology Program found that ginkgo induced mutagenic activity in the liver, thyroid, and nose of mice and rats. Over time, rodent liver underwent changes consistent with hepatic enzyme induction.³² More research is needed to clarify the role of ginkgo in this process.

Toxicity by Ingestion—Ginkgo seeds can cause food poisoning due to the compound 4’-O-methylpyridoxine (also known as ginkgotoxin).³³ Because methylpyridoxine can cause depletion of pyridoxal phosphate (a form of vitamin B₆ necessary for the synthesis of γ-aminobutyric acid), overconsumption of ginkgo seeds, even when fully cooked, might result in convulsions and even death.³³

Nomenclature and Distribution of Plants

Gingko biloba belongs to the Ginkgoaceae family (class Ginkgophytes). The tree originated in China but might no longer exist in a truly wild form. It is grown worldwide for its beauty and longevity. The female ginkgo tree is a gymnosperm, producing fruit with seeds that are not coated by an ovary wall¹⁵; male (nonfruiting) trees are preferentially planted because the fruit is surrounded by a pulp that, when dropped, emits a sour smell described variously as rancid butter, vomit, or excrement.⁵

Identifying Features and Plant Facts

The deciduous ginkgo tree has unique fan-shaped leaves and is cultivated for its beauty and resistance to disease (Figure 2).^4,34 It is nicknamed the maidenhair tree because the leaves are similar to the pinnae of the maidenhair fern.³⁴ Because G biloba is resistant to pollution, it often is planted along city streets.¹⁷ The leaf—5- to 8-cm wide and a symbol of the city of Tokyo, Japan³⁴—grows in clusters (Figure 3)⁵ and is green but turns yellow before it falls in autumn.³⁴ Leaf veins branch out into the blade without anastomosing.³⁴

Barker_2.JPG

Male flowers grow in a catkinlike pattern; female flowers grow on long stems.⁵ The fruit is small, dark, and shriveled, with a hint of silver⁴; it typically is 2 to 2.5 cm in diameter and contains the ginkgo nut or seed. The kernel of the ginkgo nut is edible when roasted and is used in traditional Chinese and Japanese cuisine as a dish served on special occasions in autumn.³³

Barker_3.JPG

Final Thoughts

Given that G biloba is a beautiful, commonly planted ornamental tree, gardeners and landscapers should be aware of the risk for allergic contact dermatitis and use proper protection. Dermatologists should be aware of its cross-reactivity with other common plants such as poison ivy and poison oak to help patients identify the cause of their reactions and avoid the inciting agent. Because ginkgo extract also can cause a cutaneous reaction or interact with other medications, providers should remember to take a thorough medication history that includes herbal medicines and supplements.

An ancient tree of the Ginkgoaceae family, Ginkgo biloba is known as a living fossil because its genome has been identified in fossils older than 200 million years.¹ An individual tree can live longer than 1000 years. Originating in China, G biloba (here, “ginkgo”) is cultivated worldwide for its attractive foliage (Figure 1). Ginkgo extract has long been used in traditional Chinese medicine; however, contact with the plant proper can provoke allergic contact dermatitis.

Barker_1.JPG

Dermatitis-Inducing Components

The allergenic component of the ginkgo tree is ginkgolic acid, which is structurally similar to urushiol and anacardic acid.^2,3 This compound can cause a cross-reaction in a person previously sensitized by contact with other plants. Urushiol is found in poison ivy(Toxicodendron radicans); anacardic acid is found in the cashew tree (Anacardium occidentale). Both plants belong to the family Anacardiaceae, commonly known as the cashew family.

Members of Anacardiaceae are the most common causes of plant-induced allergic contact dermatitis and include the cashew tree, mango tree, poison ivy, poison oak, and poison sumac. These plants can cross-react to cause contact dermatitis (Table).³ Patch tests have revealed that some individuals who are sensitive to components of the ginkgo tree also demonstrate sensitivity to poison ivy and poison sumac^4,5; countering this finding, Lepoittevin and colleagues⁶ demonstrated in animal studies that there was no cross-reactivity between ginkgo and urushiol, suggesting that patients with a reported cross-reaction might truly have been previously sensitized to both plants. In general, patients who have a history of a reaction to any Anacardiaceae plant should take precautions when handling them.

CT110001030_Table.JPG

Therapeutic Benefit of Ginkgo

Ginkgo extract is sold as the herbal supplement EGB761, which acts as an antioxidant.⁷ In France, Germany, and China, it is a commonly prescribed herbal medicine.⁸ It is purported to support memory and attention; studies have shown improvement in cognition and in involvement with activities of daily living for patients with dementia.^9,10 Ginkgo extract might lessen peripheral vascular disease and cerebral circulatory disease, having been shown in vitro and in animal models to prevent platelet aggregation induced by platelet-activating factor and to stimulate vasodilation by increasing production of nitric oxide.^11,12

Furthermore, purified ginkgo extract might have beneficial effects on skin. A study in rats showed that when intraperitoneal ginkgo extract was given prior to radiation therapy, 100% of rats receiving placebo developed radiation dermatitis vs 13% of those that received ginkgo extract (P<.0001). An excisional skin biopsy showed a decrease in markers of oxidative stress in rats that received ginkgo extract prior to radiation.⁷

A randomized, double-blind clinical trial showed a significant reduction in disease progression in vitiligo patients assigned to receive ginkgo extract orally compared to placebo (P=.006).¹³ Research for many possible uses of ginkgo extract is ongoing.

Cutaneous Manifestations

Contact with the fruit of the ginkgo tree can induce allergic contact dermatitis,¹⁴ most often as erythematous papules, vesicles, and in some cases edema.^5,15

Exposures While Picking Berries—In 1939, Bolus¹⁵ reported the case of a patient who presented with edema, erythema, and vesicular lesions involving the hands and face after picking berries from a ginkgo tree. Later, patch testing on this patient, using ginkgo fruit, resulted in burning and stinging that necessitated removal of the patch, suggesting an irritant reaction. This was followed by a vesicular reaction that then developed within 24 hours, which was more consistent with allergy. Similarly, in 1988, a case series of contact dermatitis was reported in 3 patients after gathering ginkgo fruit.⁵

Incidental Exposure While Walking—In 1965, dermatitis broke out in 35 high school students, mainly affecting exposed portions of the leg, after ginkgo fruit fell and its pulp was exposed on a path at their school.⁴ Subsequently, patch testing was performed on 29 volunteers—some who had been exposed to ginkgo on that path, others without prior exposure. It was established that testing with ginkgo pulp directly caused an irritant reaction in all students, regardless of prior ginkgo exposure, but all prior ginkgo-exposed students in this study reacted positively to an acetone extract of ginkgo pulp and either poison ivy extract or pentadecylcatechol.⁴

Systemic Contact After Eating Fruit—An illustrative case of dermatitis, stomatitis, and proctitis was reported in a man with history of poison oak contact dermatitis who had eaten fruit from a ginkgo tree, suggesting systemic contact dermatitis. Weeks after resolution of symptoms, he reacted positively to ginkgo fruit and poison ivy extracts on patch testing.¹⁶

Ginkgo dermatitis tends to resolve upon removal of the inciting agent and application of a topical steroid.^8,17 Although many reported cases involve the fruit, allergic contact dermatitis can result from exposure to any part of the plant. In a reported case, a woman developed airborne contact dermatitis from working with sarcotesta of the ginkgo plant.¹⁸ Despite wearing rubber gloves, she broke out 1 week after exposure with erythema on the face and arms and severe facial edema.

Ginkgo leaves also can cause allergic contact dermatitis.¹⁹ Precautions should be taken when handling any component of the ginkgo tree.

Oral ginkgo supplementation has been implicated in a variety of other cutaneous reactions—from benign to life-threatening. When the ginkgo allergen concentration is too high within the supplement, as has been noted in some formulations, patients have presented with a diffuse morbilliform eruption within 1 or 2 weeks after taking ginkgo.²⁰ One patient—who was not taking any other medication—experienced an episode of acute generalized exanthematous pustulosis 48 hours after taking ginkgo.²¹ Ingestion of ginkgo extract also has been associated with Stevens-Johnson syndrome.^22-24

Other Adverse Reactions

The adverse effects of ginkgo supplement vary widely. In addition to dermatitis, ginkgo supplement can cause headaches, palpitations, tachycardia, vasculitis, nausea, and other symptoms.¹⁴

Metabolic Disturbance—One patient taking ginkgo who died after a seizure was found to have subtherapeutic levels of valproate and phenytoin,²⁵ which could be due to ginkgo’s effect on cytochrome p450 enzyme CYP2C19.²⁶ Ginkgo interactions with many cytochrome enzymes have been studied for potential drug interactions. Any other direct effects remain variable and controversial.^27,28

Hemorrhage—Another serious effect associated with taking ginkgo supplements is hemorrhage, often in conjunction with warfarin¹⁴; however, a meta-analysis indicated that ginkgo generally does not increase the risk of bleeding.²⁹ Other studies have shown that taking ginkgo with warfarin showed no difference in clotting status, and ginkgo with aspirin resulted in no clinically significant difference in bruising, bleeding, or platelet function in an analysis over a period of 1 month.^30,31 These findings notwithstanding, pregnant women, surgical patients, and those taking a blood thinner are advised as a general precaution not to take ginkgo extract.

Carcinogenesis—Ginkgo extract has antioxidant properties, but there is evidence that it might act as a carcinogen. An animal study reported by the US National Toxicology Program found that ginkgo induced mutagenic activity in the liver, thyroid, and nose of mice and rats. Over time, rodent liver underwent changes consistent with hepatic enzyme induction.³² More research is needed to clarify the role of ginkgo in this process.

Toxicity by Ingestion—Ginkgo seeds can cause food poisoning due to the compound 4’-O-methylpyridoxine (also known as ginkgotoxin).³³ Because methylpyridoxine can cause depletion of pyridoxal phosphate (a form of vitamin B₆ necessary for the synthesis of γ-aminobutyric acid), overconsumption of ginkgo seeds, even when fully cooked, might result in convulsions and even death.³³

Nomenclature and Distribution of Plants

Gingko biloba belongs to the Ginkgoaceae family (class Ginkgophytes). The tree originated in China but might no longer exist in a truly wild form. It is grown worldwide for its beauty and longevity. The female ginkgo tree is a gymnosperm, producing fruit with seeds that are not coated by an ovary wall¹⁵; male (nonfruiting) trees are preferentially planted because the fruit is surrounded by a pulp that, when dropped, emits a sour smell described variously as rancid butter, vomit, or excrement.⁵

Identifying Features and Plant Facts

The deciduous ginkgo tree has unique fan-shaped leaves and is cultivated for its beauty and resistance to disease (Figure 2).^4,34 It is nicknamed the maidenhair tree because the leaves are similar to the pinnae of the maidenhair fern.³⁴ Because G biloba is resistant to pollution, it often is planted along city streets.¹⁷ The leaf—5- to 8-cm wide and a symbol of the city of Tokyo, Japan³⁴—grows in clusters (Figure 3)⁵ and is green but turns yellow before it falls in autumn.³⁴ Leaf veins branch out into the blade without anastomosing.³⁴

Barker_2.JPG

Male flowers grow in a catkinlike pattern; female flowers grow on long stems.⁵ The fruit is small, dark, and shriveled, with a hint of silver⁴; it typically is 2 to 2.5 cm in diameter and contains the ginkgo nut or seed. The kernel of the ginkgo nut is edible when roasted and is used in traditional Chinese and Japanese cuisine as a dish served on special occasions in autumn.³³

Barker_3.JPG

Final Thoughts

Given that G biloba is a beautiful, commonly planted ornamental tree, gardeners and landscapers should be aware of the risk for allergic contact dermatitis and use proper protection. Dermatologists should be aware of its cross-reactivity with other common plants such as poison ivy and poison oak to help patients identify the cause of their reactions and avoid the inciting agent. Because ginkgo extract also can cause a cutaneous reaction or interact with other medications, providers should remember to take a thorough medication history that includes herbal medicines and supplements.