Fewer allergic respiratory disorders among farmers' children in a closed birth cohort from Sweden.
The aim of this study was to investigate the prevalence of respiratory allergy, eczema and atopic sensitization in a closed birth cohort of Swedish schoolchildren, 7-8 yrs of age (n=707), of farmers and nonfarmers on the island of Gotland, in the Baltic Sea. All children were born and raised on the island. The survey comprised a questionnaire on atopic diseases and lifestyle factors. Atopic sensitization was assessed by the skin-prick test (SPT) with 15 standardized allergens. The risk ratio (RR) for ever having asthma and/or allergic rhinoconjunctivitis was significantly lower among children of farmers compared to children of nonfarmers (RR=0.38, confidence interval (CI) 95% 0.19-0.77). SPTs (test rate 92%) showed that 32% of the children had at least one positive test. Although the number of positive SPTs did not differ between the groups, there was a reduced risk among children of farmers for having both respiratory symptoms and sensitization to any International Study on Asthma and Allergy in Childhood allergen (RR=0.28, CI 95% 0.09-0.88). The present indicate that living in a farming population seems to protect against development of respiratory allergic disorders but not against allergic sensitization.