Malumfashi Endemic Diseases Research Project, XI. Water-contact activities in the schistosomiasis study area.

Fishing, bathing, swimming and playing in water were the most important activities at the Ruwan Sanyi dam site, northern Nigeria, in terms of schistosomiasis transmission. Various washing activities were important in exposure to the infection. Males were responsible for 98% of activity involving contamination and exposure. This accounted for the marked male predominance of Schitosoma haematobium infection in the Muslim communities of this area, where boys under the age of 21 years were responsible for more than 77% of environmental egg contamination. Peak water-contact activity occurred in the afternoon and this coincided with the peak cercarial shedding period and the peak urinary egg output. As a result of the construction of many such dams in this part of northern Nigeria, the recent upward trend in schistosomiasis tramission is likely to be maintained. Fishing is a new and a potentially important activity in transmission. Any future programme to control urinary schistosomiasis in this area should pay particular attention to this activity as well as group swimming activity by young males, who should be the prime target.