Selection of susceptible lines of Biomphalaria alexandrina and Bulinus truncatus snails to S.mansoni and S.haematobium infection.

Selection of progenies from infected B.alexandrina and B.truncatus snails resulted in higher infection rates. This observation was consistent when the source of micardia were from either infected human or hamsters. Infection rate of B.alexandrina increased up to 88.2% while B.truncatus did not. Compatibility between the parasites and their intermediate hosts were also studied.