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BackgroundA lower allergy and asthma prevalence in farm children has been described three decades ago in Switzerland.ObjectiveAfter years of research into bacterial exposure at farms, the origin of the farm effect is still unknown. We now hypothesize, that there is no such an effect in large industrial cattle farms with slatted floors indoors but in small farms only where animals are grazing outdoors and are having a higher endoparasite load.MethodsWe re-analyze an earlier epidemiological study by record-linkage to later agricultural surveys. The Asthma and Allergy Study in 1989/90 was a cross-sectional study of 1714 ten year old children in 63 villages covering ten different districts of Upper Bavaria. The farm effect is defined here as the association of number of cows per villager on lifetime prevalence of allergic rhinitis prevalence in the children of this village.ResultsThe farm effect is restricted to small villages only. Furthermore, districts with higher Fasciola infection rates of cows, show a significant stronger farm effect than districts with lower infection rates.ConclusionsThe results warrant further research into human immune response to endoparasites in livestock. |
