Studies on the effect of short term, high dose praziquantel treatment against protoscoleces of ovine and equine Echinococcus granulosus within the cyst, and in vitro.

Protoscoleces of Echinococcus granulosus were subjected to high concentrations of praziquantel (10-1000 micrograms/ml medium or cyst fluid) for a short, 10 min duration in vitro or in situ within cysts. Drug efficacy was then monitored either by in vitro culture in drug-free medium and/or by passage into rodents. The in vitro test of effectiveness suggested that ovine-derived protoscoleces were more sensitive than those of equine origin, and that the in vitro method of treatment was more successful than that performed in situ. However, the subsequent passage of treated protoscoleces, whether immediately after in situ or in vitro exposure or after culture in drug-free medium, indicated that the in situ administration was as effective as the in vitro treatment. Both methods reduced cyst burdens in rodents to 9-15% of control infections.