ABSTRACT
Exposure of Schistosoma mansoni cercariae to 35 or 69 ppm suspension of the dry powder of the plant Anagallis arvensis for one-hour pre-mouse exposure led to a significant reduction in worm establishment. Thus, the number of worms/mouse was 27.4 in control mice and 9.5 and 5.8 worms from mice exposed to the batches of treated cercariae. Moreover, no worms, were detected from mice exposed to cerariae previously treated for one hour with 100 ppm of the plant dry powder. Exposure of Biomphalaria alexandrina snails to miracidia hatched from ova obtained from mice infected with cercariae previously treated with 69 ppm of the plant dry powder was highly suppressed. Thus, the snail infection rate declined from 95% in control group to 58.3% in the experimental group. The mean number of cercariae shed by infected snails was 389 cercariae/ snail in the control group and 131 cercariae/snail in experimental one Moreover, the cercariae obtained from the experimental snail group were very weak and creeping on the bottom of the Petri dish, while cercariae obtained from the control group were actively swimming