Reduced risk of hay fever and asthma among children of farmers

Abstract

Background: The prevalence of atopic diseases is on the rise. Traditional lifestyles may be associated with a reduced risk of atopy.

Objectives: To test the hypothesis that children living on a farm have lower prevalences of atopic diseases. To identify differences in living conditions between farmers and other families which are associated with the development of atopic conditions.

Design: Cross-sectional survey among children entering school (aged 5-7 years). A written questionnaire including the ISAAC core questions and asking for exposures on a farm and elsewhere was administered to the parents.

Setting: School health entry examination in two Bavarian districts with extensive farming activity.

Subjects: 10 163 children.

Main outcome measures: The prevalence of doctor's diagnoses and symptoms of hay fever, asthma and eczema as assessed by parental report.

Results: Farmers' children had lower prevalences of hay fever (adjusted odds ratio = 0. 52, 95% CI 0.28-0.99), asthma (0.65, 0.39-1.09), and wheeze (0.55, 0. 36-0.86) than their peers not living in an agricultural environment. The reduction in risk was stronger for children whose families were running the farm on a full-time basis as compared with families with part-time farming activity. Among farmers' children increasing exposure to livestock was related to a decreasing prevalence of atopic diseases (aOR = 0.41, 95% CI 0.23-0.74).

Conclusions: Factors related to environmental influences on a farm such as increased exposure to bacterial compounds in stables where livestock is kept prevent the development of allergic disorders in children.