Effect of ivermectin on Toxocara canis larvae in vitro and in vivo at different migratory stages.

Abstract

INTRODUCTION: Ivermectin has shown potent activity against various nematodes. OBJECTIVE: Evaluation of the efficacy of ivermectin against Toxocara canis larvae. MATERIALS AND METHODS: In vitro assessment was conducted using larval migration inhibition test and scanning electron microscopy (SEM). In vivo, ivermectin was administered orally to mice at a single 0.2 mg/kg dose at 2 (group I), 7 (group II), or 15 days (group III) post-infection. Efficacy was evaluated through brain larval counts and histopathological examination of liver and brain. RESULTS: In vitro, ivermectin at concentrations of 10 μg/ml and 100 μg/ml inhibited larval migration by 8.5% and 87%, respectively. SEM showed cuticular damage after 24 and 48 hours with 100 μg/ml ivermectin. In vivo, brain larval counts significantly decreased in groups I and II (22.67 ± 5.41 and 37.17 ± 5.98), with no significant reduction in group III (130.5 ± 9.01). Histopathology of the liver at four weeks post-infection in groups I and II revealed numerous granulomas with degenerated larvae. The brain showed a marked reduction in larval presence and inflammation in groups I and II, while group III findings were similar to those of the control group. CONCLUSION: Ivermectin is effective against T. canis larvae during early migratory stages but shows limited efficacy against late-stage larvae.