Prevalence of asthma and allergic diseases in Sanliurfa, Turkey, and the relation to environmental and socioeconomic factors: is the hygiene hypothesis enough?

BACKGROUND The prevalence of asthma and allergic diseases has been reported to be higher in urban than in rural areas between developed and underdeveloped countries and within any given country. Studies in Turkey have yielded different results for different regions. This study aimed to investigate the prevalence of asthma and atopy in Sanliurfa, Turkey, and the influence of environmental factors. MATERIALS AND METHODS We recruited 1108 children from different areas of Sanliurfa and administered the questionnaire of the International Study of Asthma and Allergies in Childhood. Items asking for socioeconomic data were also included. Skin prick and purified protein derivative tests were performed on the children. Measles antibodies were determined and feces were analyzed for parasites. RESULTS The total prevalence of atopic diseases was 8.6% (n = 95/1108), asthma 1.9% (n=21/1108), allergic rhinitis 2.9% (n=32/1108), and allergic conjunctivitis 3.8% (n=42/1108). The rate of atopic diseases was 5.6% (n=32/573) in children attending schools in peripheral, less urban, slum areas while it was 11.8% (n=63/535) in those attending city-center schools (OR, 2.2; 95% confidence interval [CI]; 1.4-3.5; P<.001). Skin prick test positivity was observed in 3.9% (n=43/1108) overall; at schools in slum areas it was 1.9% (n=11/573), whereas at central schools the rate was 6% (n=32/535) (OR, 4.08; 95% CI, 2.03-8.20; P<.001). The prevalence of asthma and atopic diseases was significantly higher in children who have a family history of atopy, attend a central school, live in an apartment, have more rooms in their homes, and enjoy better economic conditions. CONCLUSION We found associations between various factors suggested by the hygiene hypothesis and asthma, and very low rates of prevalence of asthma and atopic diseases both in Sanliurfa in comparison with the more developed western regions and in the peripheral slum areas. The hygiene hypothesis is helpful in explaining these observations.