RESUMEN
The efficacy of cysteine inhibitor on murine Schistosom mansoni was studied when the injection of inhibitor to infected mice for 10 successive days was either starting on day 1 [group 1] or on day 21 [group2] or on day 45 [group3] post infection. Eight weeks post infection animals were sacrificed and subjected for parasitological, histological and physiological assessments. Then levels of proteases activity were assayed in normal, infected and infected treated mice in serum, livers, intestine, as well as, in S. mansoni worms and ova collected from different groups under study. Also, B. alexandrina snails were exposed to LC5, LC10 and LC25 of each of bayluscide and A. arvensis then their hemolemph protease activity were assessed after 1 day, 3 days, 1 week, 2 weeks, 3 weeks and 4 weeks of exposure and compared with that assessed in hemolemph of control snails. Both the parasitological and physiological studies gave rise to the same conclusion denoting that treatment with cysteine protease inhibitor, phenyl vinyl sulfone, at 45 day post infection could reduce the worm burden, egg tissue load, granuloma diameter, ova hatchability, proteases activity in S. mansoni worms and ova. This treatment at the same time helps mice to attain approximately normal physiological state as expressed by their serum proteases activity. The findings representing toxicity and physiology studies gave rise to the same conclusion, emphasizing that the chemical molluscicides seriously affects snail physiology exerting irreversible alterations, while plant molluscicides has effect under which snails can acclimatize their physiology to survive