Atopy and asthma in rural Poland: a paradigm for the emergence of childhood respiratory allergies in Europe

One of the more intriguing features of the epidemiologyof respiratory allergies is their distribution across Europe.Asthma and allergic rhinitis are common among childrenliving in the north-west of the continent but far rarer inmore eastern and southern populations (1). The differ-ences are about fourfold and unlikely to be explicable bygenetic variation alone. Comparisons of genetically sim-ilar populations living under different circumstancesprovide further support for one or more importantenvironmental determinants (2). International contrastsmay hide even greater local differences. In some commu-nities, children who have been brought up on farms havefar fewer atopic diseases than do their nonfarmingneighbours. This is attributed to one or more protectiveexposures that accompany a farm upbringing.The high prevalence of these diseases in countries suchas the United Kingdom and those of Scandinavia isbelieved to have arisen recently (3) although it has beendifficult to identify exactly when. The increase is often – ifloosely – attributed to westernization although, again,the relevant details of this process remain largelymysterious. Most epidemiological research in this subjectis of children. In part this is because the incidence ofallergic asthma and rhinitis is highest in childhood andimportant environmental determinants must operate atthat age; schoolchildren are also easily assembled in largenumbers. Far less is known about the distributions ofthese conditions at older ages.We report a cross-sectional survey of atopic disease intwo neighbouring populations of people aged between 5and 92 years living in Poland. We hypothesized that arural effect would be most pronounced among thechildren of these communities; but that at all ages thosewith a rural background would be less likely to haveatopic disease.Methods