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

ABSTRACT

 

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 children from an urban environment. We hypothesized that living on a farm might be protective against development of allergic sensitization and allergic diseases.

 

Methods

In a cross-sectional survey, parents of 2283 children aged 8–10 years from a mostly rural area in Austria answered a standardized questionnaire 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 of the common local allergens (18.8 vs 32.7%, P = 0.001) was significantly lower in children living on a farm than in children from a non-farming environment. In a multivariate logistic regression model, adjusting for genetic background, parent education, living and housing conditions and dietary factors did not change the odds ratio for the association of farming and allergic 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 between regular contact with farm animals and reduced risk of atopic sensitization.

 

Conclusion

Possible explanations for the lower prevalence of hay fever, asthma and allergic sensitization in children living on a farm might be the development of immunotolerance or the stimulation of TH1 cells and suppression of TH₂ cells by increased exposure of farm children to microbial antigens in the stables or farmhouses.