Comparison of Albendazole and Praziquantel therapy of Echinococcus granulosus in naturally infected sheep.

The effects of albendazole (10 mg kg-1 day-1) and praziquantel (50 mg kg-1 day-1) for 6 weeks on naturally infected sheep with pulmonary cysts of Echinococcus granulosus of proven viability were studied. Immediately following therapy, one of three sheep treated with praziquantel had viable cysts and 7 months later one of two sheep had viable cysts. One sheep died during albendazole therapy, but 7 months following therapy only one of five sheep had viable cysts. Electron microscopy demonstrated necrotic germinal layer tissue in most albendazole-treated cysts and praziquantel also had an effect on cyst ultrastructure. These data suggest that recurrence in humans treated with albendazole may be small. Whilst praziquantel was not particularly effective in this animal model, its clear effect on the ultrastructure suggests that an increased dose and combination therapy with albendazole may be more effective.