Austrian children living on a farm have less hay fever, asthma and allergic sensitization

Background and objectives In some studies, the prevalence of hay fever and asthma has been found to be lower in children from rural areas than in chil dren from an urban environment. We hypothesized that living on a farm might be protective against development of allergic sensitization and allergic d iseases. Methods In a cross-sectional survey, parents of 2283 children aged 8-10 yea rs from a mostly rural area in Austria answered a standardized questionnair e on allergic diseases and environmental factors. 1137 children performed a skin prick test to seven local allergens. Results The prevalence of hay fever (3.1 vs 10.3%, P = 0.0002), asthma (1.1 vs 3.9%, P = 0.017) and a positive skin prick reactivity to at least one o f the common local allergens (18.8 vs 32.7%, P = 0.001) was significantly l ower in children living on a farm than in children from a non-farming envir onment. In a multivariate logistic regression model, adjusting for genetic background, parent education, living and housing conditions and dietary fac tors did not change the odds ratio for the association of farming and aller gic sensitization. Only after including 'regular contact with livestock and poultry' into the model did the odds ratio change significantly (cOR 0.48 95% CI 0.30-0.75 to aOR 0.75 95% CI 0.37-1.52) indicating an association be tween regular contact with farm animals and reduced risk of atopic sensitiz ation. Conclusion Possible explanations for the lower prevalence of hay fever, ast hma and allergic sensitization in children living on a farm might be the de velopment of immunotolerance or the stimulation of TH1 cells and suppressio n of TH2 cells by increased exposure of farm children to microbial antigens in the stables or farmhouses.