It is acknowledged throughout the world that irrigation is very important in the dissemination of schistosomiasis. The present study, involving 23 irrigation projects in the semi-arid region of five northeastern states of Brazil, was conducted during the period of October 1986 to December 1987. Socio-economic-sanitary analysis identified a number of aspects of epidemiological importance, mainly the presence of migrant farm workers, coming from endemic areas of schistosomiasis and living in poor sanitary conditions in the irrigation areas. Parasitological exams of stool samples indicated that, out of 10,229 individuals examined (82% of the population), only three were S. mansoni positive. Malacological studies identified Biomphalaria straminea as the only species out of 17,188 snails captured. In only one area (São Gonçalo, district of Souza, Paraíba State), where 3,400 snails were captured, 17 were infected with S. mansoni. These results indicate that, at present, schistosomiasis transmission is not a major problem in the areas studied. However, continued epidemiological surveilance is essential in all irrigation areas of northeastern Brazil if schistosomiasis control is to be maintained. Recommendations are made for improvement in the water supply as well as for additional sanitation measures focusing on migrant workers.
Mansoni schistosomiasis; Irrigation; Epidemiology
