Prevalence and intensity of schistosomiasis in two rural areas in Zimbabwe and their relationship to village location and snail infection rates.

Surveys for schistosomiasis of 2498 people of various ages from 22 villages in northeast Zimbabwe are reported. A high prevalence of Schistosoma haematobium (53.1%) and a medium prevalence of S. mansoni (17.5%) were found. Schistosoma haematobium prevalence among males was significantly higher than among females. Age prevalence curves for both schistosome species showed a typical pattern with the peak in the ten to 20 years age group, which is also the age group with the highest potential of contaminating water with excreta. Snail surveys at 12 local sites showed the presence of Bulinus globosus and Biomphalaria pfeifferi. Both species were found shedding cercariae, and snail infection rates showed a focal distribution which could be related to the prevalence of infection in the human population.