Differences in susceptibility of Brazilian strains of Australorbis glabratus to Schistosoma mansoni

Studies were conducted to ascertain the susceptibility of the snail A. glabratus from Salvador (Bahia, Brazil) to the strain of S. mansoni from Pernambuco, Brazil. Bahian snails showed very low susceptibility when compared to a highly susceptible strain from Paulista, Pernambuco, only 1.7% of them becoming infected. Host-tissues responses of the two snail strains were markedly different. Examination of snails at intervals of 36 and 96 hours revealed that most of the invading larvae in the Bahian snails were destroyed in the tissues. On the contrary, tissue response was not seen in A. glabratus from Paulista, Pernambuco. No qualitative morphologic differences could be detected in the Bahian snails when compared to several other Brazilian strains of A. glabratus. Eighteen crosses made between members of the two strains of A. glabratus revealed that fertility was reduced when albino snails from Recife, Pernambuco, were isolated from their pigmented partners of Bahia. Evidence presented in this paper clearly suggests that the striking differences observed in the susceptibility of the two Brazilian strains of A. glabratus should be related to the snail and not to the trematode.