Effect of praziquantel on larval stages of Schistosoma japonicum.
The effect of praziquantel on S. japonicum mother sporocysts, daughter sporocysts and cercariae was studied. At concentrations of 3 X 10(-7), 3 X 10(-6) and 3 X 10(-5) M and treatment times of 24 or 48 h, mother and daughter sporocysts and young cercarial embryos were not affected but nearly mature cercariae were killed and dissociated. The resistance of young cercariae could support the suggestion that the primitive cercarial epithelium arises from the sporocyst tegument. Treatment with praziquantel always stopped cercarial emission; this cessation lasted for a few days with the lowest concentration and for up to 25 d with the highest. The duration of treatment slightly affected the pattern of reappearance of cercariae but markedly affected the long-term reduction in numbers. Free cercariae treated with praziquantel lost their tails in 10 to 60 min, depending on the concentration.
Yi
X M
XM
Chinese Academy of Preventive Medicine, Institute of Parasitic Diseases, Rui Fin Er Lu, Shanghai, People's Republic of China.
Combes
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D000818:Animals; D004305:Dose-Response Relationship, Drug; D007814:Larva / Q000187:drug effects; D011223:Praziquantel / Q000494:pharmacology*; D012549:Schistosoma japonicum / Q000187:drug effects*; D012908:Snails / Q000469:parasitology; D013997:Time Factors
D011223:Praziquantel