Another risk to US travelers—malaria

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Applied Evidence

Another risk to US travelers—malaria

J Fam Pract. 2014 November;63(11):E1-E7

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References

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Because mefloquine, doxycycline, and chloroquine target only the blood stages of Plasmodium, patients must continue these medications for 4 weeks following the exposure period to ensure adequate coverage as parasites are released from the liver. Because doxycycline is taken daily and has to be continued for 4 weeks following the exposure period, the total number of pills taken is higher for this regimen. Atovaquone-proguanil is active against hepatic and blood stages and can be discontinued a week following the exposure period.

With children, base dosing on body weight and do not exceed the recommended adult dose. When fractions of tablets are used (such as with mefloquine and atovaquone-proguanil dosing), pharmacists can crush tablets and place divided doses in capsules, to be sprinkled as needed into food such as applesauce or jelly. Mefloquine and chloroquine can be given to children of all ages and weights. Although atovaquone-proguanil is approved only for children ≥11 kg (24 lbs), dosing schedules have been calculated for children who weigh ≥5 kg.²¹Doxycycline is recommended only for children who are at least 8 years of age.

Cost. For a 2-week exposure period, chloroquine is the least expensive medication (although regions in which it is recommended are limited due to resistance) (TABLE 2^7,25,26).

Ask about accommodations

Since Anopheles mosquitoes feed between dusk and dawn, inquiring about accommodations can further clarify a patient’s malaria risk. Staying in air-conditioned housing (implying that the interior can be sealed) or that has screened windows can reduce exposure to mosquitoes, although data are lacking regarding whether the latter practice reduces the incidence of malaria transmission²⁸(SOR: C).

Share decision making

After considering the key factors determining a patient’s level of risk, you may decide to recommend no specific interventions, to advise insect avoidance measures only, to combine insect avoidance with chemoprophylaxis, or to caution against traveling to a malaria-endemic region. The patient’s contribution to the final decision includes personal preferences, values, and risk tolerance—particularly when comorbidities are involved.

When preventive measures fail

Approximately 0.2% of travelers to malaria-endemic regions will become infected, despite proper pre-travel counseling and prophylaxis.²⁹In the United States, malaria is often misdiagnosed or improperly treated.³⁰The time from initial presentation to correct diagnosis of malaria has been reported as an astonishingly high 4 to 8.5 days, depending on the population.^31,32

A high index of suspicion is needed and will ensure timely care when any febrile traveler returns from a malaria-endemic area.³³Be sure to advise patients to seek medical attention if they are feverish upon returning home.

Once suspected, the diagnosis of malaria can be readily confirmed through the use of antibody-, nucleic acid-, or microscopy-based techniques (the latter to directly visualize Plasmodium species in blood smears).

Although malaria chemoprophylaxis is relatively straightforward, malaria treatment—especially in cases of chemoprophylaxis failures—may not be, and the topic is beyond the scope of this article. For guidance on treating malaria, consult a knowledgeable physician or contact the CDC at www.cdc.gov/malaria/, or at (855) 856-4713 (weekdays, 9 am to 5 pm EST) or (770) 488-7100 (weekends or after normal business hours; ask for the Malaria Branch clinician on call).

CORRESPONDENCE
Mark K. Huntington, MD, PhD, Center for Family Medicine, 1115 East 20th Street, Sioux Falls, SD 57105; mark.huntington@usd.edu