Comparative Studies on the Characteristics of Some Geographical Strains of Schistosoma mansoni in Mice and Hamsters

In the First Report of the W. H. O. Expert Committee on Bilharziasis (1953) it was stated: “Infection with Schistosoma is often well tolerated and without clinical signs, however this relative benignity appears to vary considerably from country to country, without the cause of these variations being as yet thoroughly understood”. This statement refers to the relative absence of serious manifestations of schistosomiasis as has been reported by various investigators working in Africa, e.g. Ramsay (1934) working in Nigeria, Dixon (1934) and Fisher (1934) in the Congo, Gelfand (1950) in Southern Rhodesia, Mackey (1953) in Tanganyika, Manson-Bahr (1958) in Kenya and Nelson (1959) in Uganda as compared with the situation reported in Egypt and South America.