The effect of exposure to miracidia of Schistosoma mansoni on mortality rates of cohorts of four geographical strains of Biomphalaria pfeifferi

Abstract

First generation cohorts of 25 specimens each of parental populations of Biomphalaria pfeifferi from four different localities, were each exposed to three Schistosoma mansoni miracidia per snail at an age of four weeks. The effect on survival was evaluated by calculating the weekly per capita mortality rates and the mean life-expectancy of the exposed snails. No significant differences could be demonstrated between the per capita mortality rates of F₁ cohorts of the two parental strains originating from localities in endemic bilharzia areas. Likewise there were no significant differences in this respect as far as F₁ cohorts of the two strains originating from localities in non-endemic bilharzia areas were concerned.