Differences in susceptibility of Biomphalaria alexandrina to Schistosoma mansoni from Gize and Dakahlia Governorates, Egypt.

Biomphalaria alexandrina snails were collected from irrigation canals at Gize and Dakahlia Governorates. They were exposed to strains of Schistosoma mansoni from these localities. The snails showed different rates of susceptibility to the parasite. There was a high range of snail sensitivity to S. mansoni infection (53.9%-60.7%) when snail populations and parasite strains were from the same governorate. Supporting this was the high cercarial production from infected snails of these cases (288.2 cercariae/ snail/week of Dakahlia-Dakahlia group). However, snail populations and parasite strains from different Governorates (Gize-Dakahlia) exhibited poor values of snail sensitivity and cercarial production with significant variations from those of the group of the same governorate.