Ultrastructural modifications in Heterakis spumosa after treatment with febantel or mebendazole.

The effects of the anthelmintics febantel and mebendazole on Heterakis spumosa were investigated by means of transmission and scanning electron microscopy. Ultramorphological changes were only seen in the intestinal cells. Microtubules disappeared and granules were absent from the terminal web 12 h after treatment with either febantel or mebendazole, and up to 72 h after treatment, the number and size of autophagic vacuoles increased. Moreover the parasites became sluggish and were frequently rolled up like spiral springs. Destruction to microtubules and neurotoxic influences are discussed as possible modes of action.