[Effects of hyperinfestations by Echinostoma togoensis Jourdane and Kulo, 1981 on growth and survival of Biomphalaria pfeifferi snails].

A study of larval development of Echinostoma togoensis in Biomphalaria pfeifferi under hyperinfestation conditions (number of miradia equal to or greater than 10) showed the following characteristics: --Exposure to E. togoensis resulted in considerably increased growth in relation to the miracidial exposure dose; --Exposure to E. togoensis resulted in considerably increased mortality of B. pfeifferi. A population of Planorbs infested with 20 miracidia is completely eliminated 6 weeks after exposure. This last character, discovered for the first time in an Echinostome species, which is also a sterilizing species for the Planorb and a dominant competitor over Schistosoma mansoni, emphasizes the choice of E. togoensis as a biological control agent of intestinal schistosomiasis in Africa.