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Microbial Exposure and Incidence of Atopic Dermatitis
Early-life environmental exposures act as microbes contact carriers influencing immune system balance early in life and may lower the incidence of atopic dermatitis (AD), a new study found. Researchers conducted a matched case-control study on incident AD. Cases were 426 outpatient children with a first diagnosed incident AD. Controls were 426 children attending a pediatric/dermatologic visit for non-atopic disorders matched 1:1 to cases. Among the findings:
- The odds ratio (OR) of AD first occurrence was 0.35 for children who had experienced ≥4 infections compared with those with no infections.
- A decreasing trend in risk was observed with increasing number of siblings.
- Pet keeping was inversely associated with AD risk.
Citation:
Chatenoud L, et al. Markers of microbial exposure lower the incidence of atopic dermatitis. [Published online ahead of print July 18, 2019]. Allergy. doi: 10.1111/all.13990.
The prevalence of atopic disease has been steadily increasing in industrialized countries over past several decades. Several reasons for this have been suggested including increasing environmental pollution, improved diagnostic ability, and the hygiene hypothesis (HH). Adherents to the HH believe that reduced exposure to infectious diseases and environmental allergens, due to improved treatments and sanitation, have skewed the immune system to allow allergies to develop more rapidly. In this interesting study from Italy and France, children who had 4 or more infections had about one-third the chance of developing AD, compared to those with no reported infections during the study period. Also having pets, especially dogs, decreased the risk of AD. These data support the HH, helping us to further understand that some immune stimulations seem to reduce atopic risk. — Joseph Fowler, Jr., MD, Clinical Professor of Dermatology, University of Louisville, KY