Crete: does farming explain urban and rural differences in atopy?

Background Urban-rural differences in the prevalence of atopy and associated allergic diseases have been reported in several non-European countries. Within Europe, where such variations are less striking, a farm childhood has been postulated to be protective. Objective We aimed to compare the prevalence of atopy in urban and rural children living in Crete and to examine the role of early exposure to a farming environment in explaining any measured differences. Methods A cross-sectional survey of children attending secondary schools in Iraklion, the capital city, and five villages 100 km to the south. Atopy was determined by the responses to skin prick tests with seven common aeroallergens. Results Nine-hundred and ninety-seven children participated in the survey. 19.6% of those living in Iraklion, but only 9.6% of those from the villages, had a positive response to one or more skin prick tests. Among urban children there were significant gradients in the prevalence of atopy across several categories of animal contact and consumption of farm (unpasteurized) milk products - before the age of 5 years. These differences, however, were not apparent among the rural children.