The effect of infectious burden on the prevalence of atopy and respiratory allergies in Iceland, Estonia, and Sweden.

Background: Epidemiologic reports on the effect of microbe exposure on the development of atopy and allergic asthma are inconsistent.

Objectives: The study investigates the association between serologic markers of infections and occurrence of atopy, allergic asthma, and rhinitis among adults in Iceland, Sweden, and Estonia.

Methods: Individuals (n = 1249; mean age, 42 years) from Iceland, Sweden, and Estonia underwent a structured interview and blood sampling. Specific IgE was measured against 4 allergens, and IgG antibodies were measured against Helicobacter pylori, Toxoplasmosis gondii, hepatitis A virus, herpes simplex virus 1, Chlamydia pneumoniae, EBV, and cytomegalovirus.

Results: Nonatopic subjects more often had positive serology for Helicobacter pylori, herpes simplex virus 1, Chlamydia pneumoniae, and cytomegalovirus. Having a low number (
Conclusion: Our data are consistent with cumulative protective effect of infections against atopy and respiratory allergies irrespective of route of infection.

Clinical Implications: The study indicates what microbes or combination of microbes play a role in the complex interplay between hygiene and allergy and may contribute toward the understanding of the allergy epidemic.