Allergy: etiology and epidemiology.

The occurrence of atopic disease throughout the world is subject to many variables. Differences in methodology and diagnostic criteria for measuring the incidence could account for some disparities, but they cannot explain all of them. Despite our increasing knowledge of the atopic diseases, improved treatments, and early diagnosis, the incidence and prevalence of asthma, allergic rhinitis, and atopic dermatitis continue to rise. Ongoing research into the etiology and potential risk factors for atopic diseases could lead to the early diagnosis, effective treatment, and prevention.