Prevalence and relationship between allergic diseases and infectious diseases.

In order to determine the prevalence of childhood allergic diseases, infectious diseases, and the relationship between them, 8723 children from three junior high schools in Tou-Cheng City, Taipei County, were studied using questionnaires developed according to the International Study of Asthma and Allergies in Childhood (ISAAC) criteria combined with supplementary questions about infectious diseases. Students and their parents completed the questionnaires at home. The age of the children ranged from 10 to 18 years old (14.12 +/- 0.89 years), the majority (96.03%) was aged from 13 to 15 years old. The 12-month prevalences of self-reported allergic disease symptoms were: asthma symptom 8.2%, allergic rhinitis symptom 39.6%, and atopic dermatitis symptom 5.9%. The prevalences of diagnosis of the allergic diseases were: asthma 8.7%, allergic rhinitis 24.1%, and atopic dermatitis 3.9%. The 12-month prevalences of diagnosis of infectious diseases were: pneumonia 0.6%, bronchitis 7.2%, sinusitis 7.2%, purulent conjunctivitis 2.5%, otitis media 4.3%, encephalitis or meningitis 0.4%, gastroenteritis 14.5%, acne 23.9%, purulent dermatitis 1.3%, and other infectious diseases 1.2%. Lifetime admission rates of children due to infectious diseases were: pneumonia 1%, bronchitis 1.8%, sinusitis 0.3%, purulent conjunctivitis 0.2%, otitis media 0.3%, encephalitis or meningitis 0.3%, gastroenteritis 2.1%, and other infectious diseases 0.6%. The prevalence of infectious diseases was significantly higher in children with allergic disease symptoms (defined as asthma, allergic rhinitis, or atopic dermatitis). These results demonstrated the presence of a link between allergic diseases and infectious diseases, which may have some important clinical implications.