COMPATIBILITY OF ONE BRAZILIAN AND 2 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 Sch istosoma mansoni from different geographical areas was studied. Venezu elan snails from Barbula, Manuare (areas of schistosome transmission) and Tinaquillo (non-transmission area) and Brazilian BH snails were ex posed to infection with miracidia of both the Venezuelan YT and SM str ains and the Brazilian BH strain of S. mansoni. Snail-parasite compati bility was evaluated by quantifying the number of snails shedding cerc ariae during a period of 35 to 60 days post-infection. The best compat ibility appeared to be between the Brazilian parasites and the Brazili an or Venezuelan snails. In contrast, the Brazilian snails appeared to be resistant to infection by the Venezuelan parasites tested. Paradox ically, the compatibility between the sympatric pair of Venezuelan par asites and Venezuelan snails appeared to be lower in comparison with t he allopatric association of the Brazilian parasite and the Venezuelan snails. The results suggest an important degree of heterogeneity in t he snail and parasite isolates studied and yield biological markers fo r both organisms.