Epidemiology of schistosomiasis in the riverine population of Lagdo Lake, northern Cameroon: mixed infections and ethnic factors.

The distribution of S. mansoni and S. haematobium was evaluated using a cluster sampling technique in 15 fishing villages around Lagdo lake and 2 inland villages in northern Cameroon. The overall prevalence of S. haematobium infection was 26% and of S. mansoni was 15%, while 7% of the population sampled had mixed infections. The highest prevalences were observed in larger villages (greater than 200 persons) where sanitary conditions were poor. The intensity of S. haematobium infection in those also infected with S. mansoni was two to three times greater than in those with S. haematobium alone. Differences in prevalence among ethnic groups was attributed to occupational and cultural habits. The factors leading to the diversity of the distribution of schistosomiasis within a man-made lake are discussed.