Schistosomiasis

Abstract

Schistosomiasis is a parasitic disease which is widespread in the tropics. The parasites, schistosomes, are digenetic trematodes, which normally inhabit the veins around the bladder or bowel. There are three principal varieties of human schistosome, each with its own peculiarities, broadly corresponding to the different continents in which the disease is found: Schistosoma haematobium, which is found throughout North and Central Africa, Schistosoma mansoni, found mainly in South America and Central Africa, and Schistosoma japonicum, which is found in China, Japan and the Philippines. Their life cycles are, however, sufficiently similar for them to be treated in the same way when building qualitative models of the transmission of the disease, even though the parameters in the models may differ substantially from one species to another; the following brief account of their natural history applies in general to all three. A detailed description of most aspects of the disease is given in the excellent book by Jordan and Webbe (1969).