Development of atopic sensitization and allergic diseases in early childhood

Atopic diseases and atopic sensitization were studied from birth up to 2 y in a population-based prospective study. Physical examinations were done at 6, 12 and 24 mo, including skin-prick tests and blood samples, for the determination of serum IgE level and circulating IgE antibodies to food and inhalant allergens. In addition, questionnaire surveys were done about clinical symptoms of allergy, infections and the home environment. At 2 y the prevalences of definite and probable atopic diseases were 17% and 13%, respectively. The cumulative incidence of allergy was 25%. Atopic dermatitis was the main manifestation of atopy, with a peak prevalence of 15% at 2 y. The prevalence of positive skin-prick tests was constant at all ages, i.e. 7% at 6, 12 and 24 mo. Positive skin-prick tests against inhaled allergens were more than twice as common at 24 than at 12 mo, while sensitivity to food decreased. In contrast, circulating IgE antibodies to egg became more common with age, reaching 20% at 2 y. Conclusions: The present study indicates that manifestations of allergic diseases and incidence of sensitization to foods and inhalants are equally common in Estonian and Scandinavian children during the first 2 y of life, despite a much lower prevalence among older children and adults in Estonia.