A review of the use of non-residual molluscicides in the Transvaal.

The non-residual molluscicides mainly used in the Transvaal for bilharziasis control are copper sulfate and sodium pentachlorophenate. The author reviews previous experience with these compounds in the Transvaal and discusses the physical and epidemiological conditions bearing on their use there.Extensive field trials with copper sulfate have shown that it does not sufficiently reducé the incidence of Schistosoma mansoni or S. haematobium to warrant the expense of a control programme based on it. Sodium pentachlorophenate is not of much greater value since it is rapidly broken down by sunlight in the clear waters of the Transvaal.It is concluded that use of non-residual molluscicides cannot be recommended as a general control measure in the Transvaal although they might usefully be applied as an adjunct to other methods of bilharziasis control.