Compatibility of one Brazilian and two Venezuelan strains of Schistosoma mansoni with various strains of Biomphalaria glabrata.

For evaluation of the degree of genetic heterogeneity in parasite and snail strains, the compatibility between Biomphalaria glabrata and Schistosoma mansoni from different geographical areas was studied. Venezuelan snails from Bárbula, Manuare (areas of schistosome transmission) and Tinaquillo (non-transmission area) and Brazilian BH snails were exposed to infection with miracidia of both the Venezuelan YT and SM strains and the Brazilian BH strain of S. mansoni. Snail-parasite compatibility was evaluated by quantifying the number of snails shedding cercariae during a period of 35 to 60 days post-infection. The best compatibility appeared to be between the Brazilian parasites and the Brazilian or Venezuelan snails. In contrast, the Brazilian snails appeared to be resistant to infection by the Venezuelan parasites tested. Paradoxically, the compatibility between the sympatric pair of Venezuelan parasites and Venezuelan snails appeared to be lower in comparison with the allopatric association of the Brazilian parasite and the Venezuelan snails. The results suggest an important degree of heterogeneity in the snail and parasite isolates studied and yield biological markers for both organisms.