The effect of varying the number of Schistosoma mansoni miracidia on the reproduction and survival of Biomphalaria pfeifferi

The number of young snails emerging from egg masses of Biomphalaria pfeifferi (Kampala strain) is reduced by exposure to an increasing number of miracidia of Schistosoma mansoni (West Nile strain). Snails exposed to four miracidia are rendered sterile. Survival of infected snails is inversely proportional to the number of miracidia to which an individual snail is exposed.