Epidemiology of Schistosoma mansoni infection on the Kano Plain of Kenya.
1. The results of a survey of 740 school children showed a very low prevalence of S. mansoni infection on the Kano Plain; no infected children were found in 7 out of 16 schools examined and the highest infection rate was 23•9%. The infection was confined to a narrow belt round lake swamps; no infection was found over most of the plain. Similar results were obtained in a survey of 11 schools in Nyakach, an area adjoining the plain to the south-west.. Biomphalaria sudanica, 2. which occurred only in swamps, was the only Biomphalaria species found in an extensive search for vectors of schistosomiasis. S. mansoni was isolated from the snail. From this isolation and from the distribution of the snail and the infection, it is concluded that B. sudanica is the principal, and probably the only, intermediate host of S. mansoni on the Kano Plain.