THE DEVELOPMENT OF IRRIGATION AND ITS INFLUENCE ON THE TRANSMISSION OF BILHARZIASIS IN TANGANYIKA.

Schistosoma mansoni and Schistosoma haematobium are widely distributed throughout East Africa, each being transmitted by several intermediate hosts. It is feared that the increased use of irrigation, which is proposed in Tanganyika to expand agricultural productivity, will also increase the incidence and intensity of schistosomal infection. Nine newly developed irrigation schemes have been examined to provide base-line data against which any future observations on the build-up of bilharziasis can be compared. A description is given in tabular form of each scheme together with the results of snail and parasite surveys conducted on and around it. These results are discussed in relation to the type of scheme and in the light of existing knowledge of bilharziasis in East Africa. The necessity and suitability of certain control measures are discussed.