Studies on the transmission of schistosoma haematobium and the bionomics of bulinus (ph.) abyssinicus in the somali democratic republic

Abstract

Studies were carried out from April 1977 to November 1978 on the transmission of Schistosoma haematobium and on the bionomics of its intermediate snail host, Bulinus abyssinicus, in Koryole and Merca Districts, Somalia. In Koryole, snail populations and the numbers of infected snails on the east side of the Shebelli River exceeded those on the west side. The overall snail infection rate for Koryole was 1·;7% (69/4103). In Merca, snail populations and the numbers of infected snails were higher than in Koryole. The overall snail infection rate for Merca was 1·6% (152/9509). Snails and S. haematobium infections were found mainly in standing-water. Snails were unable to establish themselves in irrigation canals because the water in the canals was fast-flowing, there were no plants to provide food and substrate and the canals were allowed to dry out and to be dug out frequently, rendering them unsuitable as snail habitats. Also, snails were unable to aestivate and survive in dry mud for long periods. © 1981 Liverpool School of Tropical Medicine.