Echinococcus multilocularis: ultrastructural effect of in vivo albendazole and praziquantel therapy, singly and in combination.

Cotton rats with Echinococcus multilocularis infections of one month's standing were treated for six months with albendazole (50 mg kg-1 day-1), or praziquantel (500 mg kg-1 day-1), or both drugs simultaneously. The germinal layer of albendazole-treated cysts differed little from control tissue apart from marginal increase in cyton vesiculation and the presence of small lamellated residual bodies. Protoscolex tissue appeared unaffected. The germinal layer of praziquantel-treated cysts differed markedly from control tissue, with increased vesiculation and mitochondrial number in those with intact germinal layers, and disintegration and detachment of the layer in other cysts. Protoscoleces were necrotic. After combined therapy, the germinal layer was either intact but with increased vesiculation and residual bodies present, or was disintegrating and detaching from the laminated layer.