Effect of various foods on Biomphalaria alexandrina and Bulinus truncatus and their susceptibility to schistosome miracidia

The tested foods are tropical fish food (tetramine), rat food, blue green algae, dried lettuce leaves and a mixture of all these foods. The results indicated that feeding of B. alexandrina on a mixture of foods increased their growth and survival rates and their susceptibility to S. mansoni. Tetramine elevated the egg-laying capacity of snails compared to other tested foods. The hatchability of eggs of B. alexandrina fed on algae for a period of 16 weeks showed the highest rate followed by snails fed on a mixture of foods and then tetramine. B. truncatus maintained on a mixture of foods for 16 weeks, exhibited an increase in their growth, egg-laying, survival rates and recorded the highest infection rate with S. haematobium than other foods. Among the used foods, the hatchability of eggs of B. truncatus fed on tetramine for 16 weeks was the highest one.

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.

Effect of X-ray on the snails of schistosomiasis in Egypt

Biomphalaria alexandrina and Bulinus truncatus snails were exposed to sublethal doses 0.2, 3, 5, 10 and 20 rad of X-ray. The survival and reproductive rates of these snails were highly affected by these doses. The maximum survival periods of laboratory populations of Biomphalaria snails were less than those of field ones which means a high sensitivity of laboratory snails to X-ray. The reproductive capacity of irradiated Biomphalaria and Bulinus snails was highly suppressed and this will interrupt Schistosomiasis transmission. A deleterious effect of gametogenesis of irradiated Biomphalaria was histologically proved. After 3 weeks of snail irradiation with high dose (40 rad) the hermaphrodite gland became completely evacuated.