The effect of area-wide snail control on the endemicity of bilharziasis in Egypt.

Molluscicides applied to two areas near Alexandria had a significant effect in reducing both incidence and prevalence of Schistosoma haematobium and S. mansoni infections. No decrease in either measure of endemicity was found in an adjacent untreated area. Bayluscide and sodium pentachlorophenate were equally effective in interrupting the transmission of S. haematobium, but Bayluscide was more effective against S. mansoni, probably because of the difficulty of applying sodium pentachlorophenate to drains, which are the primary habitats for the intermediate hosts of S. mansoni. The authors believe that the present experiment provides strong evidence of the interruption of transmission of bilharziasis in the Nile Valley or Delta.