Cross-sectional studies on Schistosoma mansoni infection in northeast Brazil

Studies on the prevalence and morbidity of Schistosoma mansoni infection were carried out in selected areas of northeastern Brazil. The study revealed that both prevalence and morbidity rates were significantly higher in rural than in urban areas. No statistically significant differences in prevalence and morbidity were found in relation to sex. The age-specific prevalence curve was found to be of the usual shape found in highly endemic areas of the country: it reaches its peak in the 10-14 group, and slightly decreases in the older groups. Although it is generally admitted that hepatosplenic forms of the disease occur more frequently between 10 and 40 years of age, the present study has shown that the proportion of these severe cases increases with increase of age.