Background-The development of asthma seems to be influenced by the adoption of a Western lifestyle. A study was undertaken to assess the importance of indoor environmental factors in Nepal where the lifestyle and home environment diVer from that in the West. Methods-The home environment of 121 schoolchildren with asthma and 126 controls aged 11-17 years was studied. The homes of all participants were investigated and the children and their mothers were interviewed using a standardised questionnaire. Cases and controls were identified from an ISAAC (International Study of Asthma and Allergy in Childhood) based population study of 2330 schoolchildren in Kathmandu, Nepal. Results-Keeping cattle inside the house during the night was related to a lower risk for having asthma (adjusted odds ratio (OR) 0.2 (95% CI 0.1 to 0.5)) while there was no association between asthma and cattle kept outside. Asthma was associated with cigarette smoking by two or more family members (OR 1.9 (95% CI 1.0 to 3.9)) and with the domestic use of smoky fuels (OR 2.2 (95% CI 1.0 to 4.5)). In analyses stratified by sex, passive smoking and the use of smoky fuels were significantly associated with asthma only in boys. Conclusions-The risk of asthma in Nepalese children was lower in subjects exposed to cattle kept inside the house and higher in subjects exposed to passive smoking and indoor use of smoky fuels. Childhood exposure to microorganisms or allergens from cattle may protect against the development of atopic disease. (Thorax 2001;56:477-481) Keywords: asthma; domestic animals; smoky fuels; passive smoking; infection hypothesis; microbial stimulation Epidemiological studies suggest that the development of asthma may be influenced by the adoption of a Western lifestyle.1 2 The International Study on Asthma and Allergies in Childhood (ISAAC) showed a significant worldwide variation in the prevalence of symptoms of asthma, with the highest prevalence in English speaking Western countries and the lowest prevalence in Eastern Europe and Asia. In the Western world diVerent populations may be exposed to risk factors for asthma in a similar way. Aetiological patterns may be more evident when comparisons are made between more diVerent cultures. A study was undertaken to assess the importance of indoor environmental factors potentially relevant for asthma in Nepal, a country where the lifestyle and home environment is diVerent from that in the West.Atopic diseases are reported to be more common in children exposed to animal dander than in those not exposed.4 5 On the other hand, findings from the European Community Respiratory Health Survey indicate that dog keeping in early childhood protects against adult atopy.6 A study of Swedish children revealed less asthma and allergic rhinitis in children who had a pet during their first year of life.7 Furthermore, recent studies of allergy in a farm environment provide evidence of less hay fever and asthma among children of farmers. [8][9][10] In Nepal a large proportion of the population are...

BACKGROUNDThe development of asthma seems to be influenced by the adoption of a Western lifestyle. A study was undertaken to assess the importance of indoor environmental factors in Nepal where the lifestyle and home environment differ from that in the West.METHODSThe home environment of 121 schoolchildren with asthma and 126 controls aged 11–17 years was studied. The homes of all participants were investigated and the children and their mothers were interviewed using a standardised questionnaire. Cases and controls were identified from an ISAAC (International Study of Asthma and Allergy in Childhood) based population study of 2330 schoolchildren in Kathmandu, Nepal.RESULTSKeeping cattle inside the house during the night was related to a lower risk for having asthma (adjusted odds ratio (OR) 0.2 (95% CI 0.1 to 0.5)) while there was no association between asthma and cattle kept outside. Asthma was associated with cigarette smoking by two or more family members (OR 1.9 (95% CI 1.0 to 3.9)) and with the domestic use of smoky fuels (OR 2.2 (95% CI 1.0 to 4.5)). In analyses stratified by sex, passive smoking and the use of smoky fuels were significantly associated with asthma only in boys.CONCLUSIONSThe risk of asthma in Nepalese children was lower in subjects exposed to cattle kept inside the house and higher in subjects exposed to passive smoking and indoor use of smoky fuels. Childhood exposure to microorganisms or allergens from cattle may protect against the development of atopic disease.