[Prevalence of asthma, allergic rhinitis and atopic dermatitis in school children of the Mexican Bajío region].

Background: The prevalence of allergic diseases markedly varies according to the geographical region.

Objective: To determine the prevalence of asthma, allergic rhinitis and atopic dermatitis in children of six and seven years of age.

Methods: Cross-sectional study that included a sample of almost 15 thousand children in five cities of Mexico.