[Experimental schistosomiasis III. Observations on the infestation of Biomphalaria glabrata by a miracidium of Schistosoma mansoni].

380 B. glabrata infected with 1 miracidium of S. mansoni produced 87 positive snails (22,9%), 38 of which sending out male cercariae and 49 female cercariae. The snails belonged to 3 experimental series kept at 27 degrees and 24 degrees C for 15 weeks under continuous lighting. There was no difference between the proportions of both sexes. The survival of the positive snails was favoured by the male sex. The shedding of female cercariae was greater than shedding of male. During those 15 weeks, the cercarial shedding of both sexes showed large and recurring changes. A certain correlation seems to exist between the sex of cercariae, the abundance and the frequency of cercarial shedding, and the longevity of the parasitized snails. All those factors could take a part in the epidemiology of the schistosomiasis.