The Frequency of Bisexual Infections of Schistosoma mansoni in Snails of the Species Australorbis glabratus (Say)

Abstract

The sex of the schistosomes developing in individual snails exposed in the laboratory to numbers of miracidia varying from 1 to 20 has been observed upon maturation of the parasites in mice. All the infections originating from one miracidium were unisexual; 76% of the 20-miracidial exposures were bisexual. Bisexual infections from 2-, 3-, 4-, 5-, and 10-miracidial exposures varied from 28 to 52% of the total infections studied. Male and female infections occurred approx. in a 1:1 ratio. Individual Australorbis glabratus were refractory to this Puerto Rican strain of S. mansoni in varying degrees.