Risk Factors for Asthma in a Helminth Endemic Area in Bahia, Brazil

Abstract

Protective factors associated with atopy or asthma in rural areas include socioeconomic level, overcrowding, and helminth infection. However, little epidemiological information was originated from schistosomiasis areas. This study aimed to investigate factors associated with asthma in a schistosomiasis endemic area. A questionnaire was used to obtain information on demographics, socioeconomic, and environmental features. The ISAAC questionnaire was used to identify individuals with asthma. Parasitological exam was done in all participants and skin prick test to aeroallergens in all asthmatics. Prevalence ofSchistosoma mansoniinfection was 57.4% andAscaris lumbricoides,30.8%. Asthma was found in 13.1% of the population, and 35.1% of them had a positive SPT. Active and passive smoking was positively associated with asthma, whereasA. lumbricoideswas negatively associated. In a schistosomiasis hyperendemic region, current infection withA. lumbricoidesis protective against asthma. However, we cannot rule out the involvement ofS. mansoniinfection in this process.