RESUMEN
Water collected from trays containing Biomphalaria alexandrina infected with Schistosoma mansoni at the time of cercariae shedding [SmISW] and trays containing clean, non-infected, B. Alexandrina [NISW] and underground water [UW], were filtered used as a drinking water for 3 groups of albino mice males. After 2 months, blood samples were collected from the 3 groups and serum was tested for anti-cercarial IgG, then mice were infected with 150 S. Mansoni cercariae. 8 weeks after infection, mice were perfused and adult S. mansoni worms were counted. Anti-cercarial IgG was positive in 23 out of the 28 samples collected from mice drinking SmISW and only in 2 out of the 21 samples collected from mice drinking NISW, while all samples collected from mice drinking UW were negative for anti-cercarial IgG [X2 = 45.897, P <0.001]