Urban-rural differences in questionnaire-derived markers of asthma in Kenyan school children

Grade 4 Kenyan children attending 10 randomly selected public primary schoo ls in Nairobi (urban) and the Muranga District (rural) were surveyed to est ablish the prevalence of symptom markers of asthma and to assess the impact of urbanization. A respiratory health and home environment questionnaire was administered at school to parents or guardians. The questionnaire response rates were 94.2 % (568/603) for Nairobi and 89.6% (604/674) for Muranga, The prevalence rates for asthma, defined as "attacks of shortness of breath with wheeze",were 9.5% for urban and 3.0% for rural children (odds ratio ( OR) urban versus rural: 3.42; 95% confidence interval (CI): -1.96-5.91). Th is urban-rural gradient persisted after adjusting for urban-rural differenc es in host factors (including duration of breastfeeding and family history of asthma and/or allergy), but was largely explained by urban-rural differe nces in environmental factors, including indoor animals, sharing a bedroom with a smoker, parental education, house ventilation and exposure to motor vehicle fumes en route to school (adjusted OR: 1.59; 95% CI: 0.70-3.55). Si milar results were obtained for all other symptoms. These findings confirm the clinical impression that asthma is an important illness in Kenya and underline the need for the further study of environmen tal factors amenable to intervention, particularly in urban areas.