Effects of praziquantel on human intestinal flukes (Fasciolopsis buski and Heterophyes heterophyes).

Human intestinal flukes (Fasciolopsis buski and Heterophyes heterophyes) were treated with praziquantel in vivo or in vitro and then studied by transmission (TEM) and scanning (SEM) electron microscopy. F. buski worms recovered from patients, which had been cured by oral treatment of 1 X 15, 1 X 25 or 1 X 40 mg praziquantel/kg body weight, showed typical contraction and alterations together with vacuolization and bleb formation of their tegument. H. heterophyes worms recovered from an experimentally infected dog were incubated in media containing 1 microgram praziquantel/ml for 5-60 min. Their tegument showed lesions the extent and duration of which increased with exposure time, finally leading to death. The damage observed in vitro was very similar to that found in F. buski recovered from cured patients. The cure rate was very high when using 1 X 15 mg praziquantel/kg.