Primary care physicians (PCPs) play a key role in treating young patients as they progress through the “atopic march” from atopic dermatitis through food allergy, asthma, and allergic rhinitis. They can also help prevent the process from starting.
“The PCP is usually the first clinician a family with concerns about atopic conditions sees, unless they first visit urgent care or an emergency department after an allergic reaction to food. Either way, families rely on their PCP for ongoing guidance,” said Terri F. Brown-Whitehorn, MD, attending physician in the Division of Allergy and Immunology at the Center for Pediatric Eosinophilic Disorders and the Integrative Health Program at Children’s Hospital of Philadelphia.
“The most important thing PCPs can do is know that the atopic march exists, how it progresses over time, and what signs and symptoms to look for,” she told this news organization.
The Atopic March
The atopic march describes the progression of allergic diseases in a child over time, with atopic dermatitis and food allergy in infancy tending to be followed by allergic rhinitis and asthma into later childhood and adulthood.
Although the pathophysiology of the inflammation that precedes atopic dermatitis is unclear, two main hypotheses have been proposed. The first suggests a primary immune dysfunction leads to immunoglobulin E (IgE) sensitization, allergic inflammation, and a secondary disturbance of the epithelial barrier; the second starts with a primary defect in the epithelial barrier that leads to secondary immunologic dysregulation and results in inflammation.
Genetics, infection, hygiene, extreme climate, food allergens, probiotics, aeroallergens, and tobacco smoke are thought to play roles in atopic dermatitis. An estimated 10%-12% of children and 1% of adults in the United States have been reported to have the condition, and the prevalence appears to be increasing. An estimated 85% of cases occur during the first year of life and 95% before the age of 5 years.
“Atopy often, though not always, runs in families, so PCPs should inquire about the history of atopic dermatitis, IgE-mediated food allergies, allergic rhinitis, and asthma in the patient’s siblings, parents, and grandparents,” Brown-Whitehorn said.
Key Educators
PCPs treat the full gamut of atopic conditions and are key educators on ways families can help mitigate their children’s atopic march or stop it before it begins, said Gerald Bell Lee, MD, an allergist and immunologist at Children’s Healthcare of Atlanta and an associate professor in the Division of Allergy and Immunology at Emory University School of Medicine, Atlanta.
“Most parents who bring their infants with eczema to the PCP assume their child ate something that caused their rash. But the relationship between atopic dermatitis, a type of eczema, and food allergy is more complicated,” he added.
Lee said PCPs should explain to their patients what atopic dermatitis is, how it starts and progresses, and how families can help prevent the condition by, for example, introducing allergenic foods to infants at around 4-6 months of age.
Atopic Dermatitis
PCPs should inform parents and other caregivers to wash their hands before moisturizing their child, take care not to contaminate the moisturizer, and bathe their child only when the child is dirty.
“Soap removes protective natural skin oils and increases moisture loss, and exposure to soap and bathing is a main contributor to eczema,” said Lee. “Dry skin loses its protective barrier, allowing outside agents to penetrate and be identified by the immune system.”
“According to one hypothesis, parents may eat food, not wash their hands afterwards, then moisturize their baby. This unhygienic practice spreads food proteins from the adult’s meal, and possibly from contaminants present in the moisturizer, all over the baby’s body,” he added.
Lee said he and his colleagues discourage overbathing babies to minimize the risk for skin injury that begins the atopic march: “New parents are inundated with infant skincare messaging and products. But we need to weigh societal pressures against practicality and ask, ‘Is the child’s skin actually dirty?’ ”
Atopic dermatitis tends to appear on the extensor surfaces, face, and scalp in infants and around arm and leg creases in toddlers and older children. Severe forms of the condition can be more widely distributed on the body, said Aarti P. Pandya, MD, medical director of the Food Allergy Center at Children’s Mercy Kansas City and clinical assistant professor of pediatrics at the University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
Avoid Triggers, Minimize Flares
Triggers of eczema are varied and common. To help minimize flares, PCPs can encourage caregivers to avoid products with fragrances or dyes, minimize the use of soaps, and completely rinse laundry detergent from clothing and household items. “Advise them to keep fingernails short and control dander, pollen, mold, household chemicals, and tobacco smoke, as well as the child’s stress and anxiety, which can also be a trigger,” Lee said.
“Skin infections from organisms such as staph, herpes, or coxsackie can also exacerbate symptoms,” Brown-Whitehorn added. “PCPs can educate caregivers to avoid all known triggers and give them an ‘action plan’ to carry out when skin flares.”
Food Allergies
Parents may be unaware food allergens can travel far beyond the plate, Lee said. Researchers vacuuming household bedding, carpets, furniture, and other surfaces have detected unnoticeably tiny quantities of allergenic food proteins in ordinary house dust. Touching this dust appears to provide the main exposure to those allergens.
“According to the dual exposure to allergen hypothesis, an infant’s tolerance to antigens occurs through high-dose exposure by mouth, and allergic sensitization occurs through low-dose exposure through the skin,” he said. “As young as four to six months of age, even before eating solid food, a child develops eczema, has a leaky skin barrier, comes in contact with food, and develops a food allergy.”
IgE-mediated food allergies can begin at any age. “Symptoms occur when a food is ingested and the patient develops symptoms including but not limited to urticaria, angioedema, pruritus, flushing, vomiting, diarrhea, coughing, wheezing, difficulty breathing, presyncope, or syncope,” Pandya noted.
In the case of eosinophilic esophagitis, which may also be part of the atopic march, infants and toddlers often have challenging-to-treat symptoms of reflux, while school-age children have reflux and abdominal pain, and adolescents and adults may experience difficulty swallowing and impactions of food or pills, Brown-Whitehorn said.
To differentiate between food allergy and contact dermatitis, Lee suggested providers ask, “ ’Is the rash hives? If yes, is the rash generalized or in a limited area?’ Then consider the statistical probabilities. Skin problems after milk, egg, wheat, soy, peanut, tree nut, fish, shellfish, or sesame are likely due to IgE-mediated food allergy, but after ketchup or strawberry are probably from skin contact.”