Childhood asthma and continuous exposure to cats since the first year of life with cats allowed in the child's bedroom.

BACKGROUND There are controversial data as to interdependencies of exposure to furred pets in infancy and the prevalence of asthma and hay fever in children. Does the timing, intensity and type of pet exposure matter? METHODS Cross-sectional questionnaire data on 8216 German schoolchildren aged 5-7 years not living on a farm in ten rural districts in Bavaria in 1997 were analysed. The diagnosis of asthma and hay fever was ascertained with the International Study of Asthma and Allergies in Childhood (ISAAC) core questions. Wheeze and asthma were classified as 'atopic' in children who also had hay fever or atopic dermatitis. Prevalence and intensity of exposure to pets in the first year of life and at present were assessed via questionnaire. RESULTS Although the study was of considerable size we found no convincing association between atopic disease and pet exposure in general. Exposure to cats from the first year of life to school entry, however, was associated with a reduced prevalence of atopic asthma, if cats were allowed to be in the child's bedroom: no case of atopic asthma in 296 children exposed and an aOR 0.11 (95% CI:0.01-0.52) for atopic wheeze in the last 12 months. CONCLUSIONS Allowing cats to be in the child's bedroom from the first year of life onwards may be an indicator of intensive exposure to cats and appears to prevent the development of childhood asthma.