Infections in child day care centers and later development of asthma, allergic rhinitis, and atopic dermatitis: prospective follow-up survey 12 years after controlled randomized hygiene intervention.

OBJECTIVE To evaluate the effect of successful prevention of common infections in child day care centers on the later development of allergic diseases. DESIGN Prospective follow-up survey with a questionnaire administered 12 years after a controlled randomized hygiene intervention. SETTING Twenty municipal child day care centers in Oulu, Finland. PARTICIPANTS A questionnaire was sent to 1354 prior participants (98%) in the intervention trial. The response rate was 68% (928 of 1354 participants). MAIN INTERVENTION: Hygiene intervention from March 1, 1991, to May 31, 1992. MAIN OUTCOME MEASURES The number of respondents who had a diagnosis of asthma, allergic rhinitis, and/or atopic dermatitis made by a physician, and the number of those who reported symptoms of atopic diseases. RESULTS Asthma was diagnosed by a physician in 48 of the 481 respondents (10%) from the intervention child day care centers, with markedly fewer infections, and in 46 of the 447 controls (10%) (relative risk, 1.0; 95% confidence interval, 0.7-1.4). Similarly, no differences were found in the numbers of children who had a diagnosis of other atopic diseases or who had reported such symptoms. CONCLUSION The prevention of common respiratory tract and enteric infections during early childhood does not change later allergic morbidity.