الفهرس 
Factors affecting rearing and maintenance of snailsOnly 14 pages are availabe for public view
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Abstract
This study was conducted to clarify the effect of eight chosen compounds namely ni~losamiden~ic lofolan, rafoxanide, copper sulfate, levamisole Hcl, praziquantel, mebendozole and triclabendazole against different stages of chist to soma mansoni and Fasciola spp., their intermediate hosts (Biomphalaria nlexandrina and Lynznaea spp.) and the embryonated eggs of the snails. The study showed that niclosamide,niclofolan, rafoxanide and copper sulfate respectively were the most effective compounds against B.alexancin’na and Lyntnaea spp. snails and their embryonated eggs,whiie levamisole and praziquantel were less effective .On the other hand,mebendazoIe and triclabendazole were ineffective against the snails and their embryonated eggs. Regarding the efficacy of the used drugs against the miracidia of both parasites, it was found that niclosamide was more effective on miracidia of Fascioln than that of Schistosoma (10 pprn in case of Fasciola miracidia and 20 pprn in case of Schistosoma miracidia). Niclofolan showed activity against both miracidia at 1 ppm. The antifascioliasis, rafoxanide was more effective against Fasciola miracidia than those of Schistosoma ,since it was effective against miracidia of Fnsciola at 0.1 pprn and at lppm in case of Schistosoma miracidia. Copper sulfate showed efficacy against Schistosoma miracidia at lOppm and at 1 pprn in case of Fasciola miracidia. The antischistosomal drug praziquantel was more effective against Schistosoma miracidia than that of Fasciola since it killed Schistosoma miracidia at 0.1 pprn but it was eflective only on Fasciola miracidia at 10ppm. Also the antifascioliasis drug triclabendazole was effective against Fasciola miracidia at 1 pprn and at 10 pprn in case of Schistosoma miracidia. On the other hand levamisole and mebendazole had no effect on the miracidia of both parasites at 20 ppm. Praziquantel was the only drug which showed activity against the intramolluscan stages of S.mansoni, since it completely eradicated the parasite from the infected Bionzphalaria snails at concentration of 3 pprn after 4 days exposure. On the other sidq,niclofolan at 0.05 pprn, praziquantel at 1 ppm and mebendazole at lOppm completely suppressed cercarial shedding of infected Lymnaea snails with Fasciola spp. and greaty reduced the intra-molluscan stages of the parasite within the snails after four days exposure. Regarding the eficacy of the chosen drugs against cercariae of S.mansoni and Fnsciola spp., it was found that niclosamide , niclofolan, rafoxanide and praziquantel were effective against cercariae of both parasites at 0.1 ppm.Copper suflate showed activity against Schistosoma cercariae at concentration of 0.lppm while the cercariae of Fasciola were susceptible to copper sulfate only at l0ppm. Levamisole and triclabendazole were effective against cercariae of both parasites at 10 ppm. On the other hand,mebendazole had no effect on both cercariae at concentration of 20 pprn . pr=iqumtel , niclofolan and niclosamide showed great activity against in vitro cultivated adult S.mansoni , since 1 pprn of these drugs killed the worms after 1,4 and 6 hours respectively.However lOOppm copper sulfate gave 100% mortality for adult Schistosoma after 48 hr. On the other hand,rafoxanide, levamisole, mebendazole and triclabendazole had no effect on adult S.mansoni in vitro at concentration of 100 pprn after three days exposure. The results showed that niclofolan,rafoxanide and niclosamide were effective against in vitro cultivated adult Fasciola spp. at a concentration of lipprn,while levamisole and praziquantel were only effective against Fasciola worms at concentrations of 10 and 100 pprn respectively. On the other hand copper sulfate, triclabendazole and mebendazole had no effect on adult Fasciola at concentr-ation of 100 pprn after three days exposure. The postmortem ultra-structural changes in the tegument and suckers of schistosomes,treated with 10 ppm niclosamide for two hourpin vitro showed swellir~g of the worms,retraction of the suckers,formation of blebs on the suckers and the tegument,destruction of spines and the tegument became partially collapsed. The postmortem changes in the tegument of schistosome~treatedw ith 10 ppm niclofolan for ’h hr. ,in vitro showed distortion and swelling of the worms, secretion of organic material to which debris have attached , retraction of suckers,destruction of spines and formation of blebs on the tegument and the suckers. while the control did not show any of this upnormal changes. The postmortem changes in the tegument of Fasciola spp. treated with 25 ppm niclosamide for 2 ’h hr-,demonstrated that the ventral suckers of the worm became obliterated and the ruptured blebs (crater) appeared arround it. The spines on the dorsal surface became submerged due to swelling of the plateaux and the tegument of ventral surface was infolded.