[Effect of the hybridization of Schistosoma mansoni strains on the degree of compatibility of the parthenitae with their mollusk intermediate hosts].

After-effects of hybridization of S. mansoni strains, having Biomphalaria pfeifferi as an intermediate host, have been revealed for the first time. The crossing of two african strains (malarial-M and guinea-G), which have different compatibility rates with their specific intermediate hosts, has shown that hybrids display a higher virulence in respect to molluscs-hosts than maternal strains. The compatibility rate of the first generation hybrids with B. pfeifferi decreased, the breachs in the compatibility being the more significant the higher the degree of adaptation between the maternal strain and specific intermediate host. The infectiousness of the second generation hybrids in respect to molluscs of two populations of B. pfeifferi (M and G) virtually did not differ and varied in the ranges of mean values between the initial infectiousness of two maternal strains.