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

Abstract

Introduction. Current anthelmintic treatments for toxocariasis exhibit moderate efficacy. Ivermectin has demonstrated potent activity against various nematodes.
Objective. To evaluate the efficacy of ivermectin against Toxocara canis larvae.
Material and methods. In vitro evaluation was done using larval migration inhibition test and scanning electron microscopy. In vivo, ivermectin was administered orally to the mice as a single dose of 0.2 mg/kg body weight at two (group I), seven (group II), or 15 days (group III) post-infection (p.i.). The efficacy of the drug was assessed through larval counts in the brain and histopathological examinations of the liver and brain.
Results. In the larval migration inhibition test, ivermectin at concentrations of 10 µg/ml and 100 µg/ml inhibited larval migration by 8.5% and 87%, respectively. Scanning electron microscopy revealed damage to the larval cuticle after 24 and 48 hours of incubation with 100 µg/ml ivermectin. In the in vivo test ivermectin significantly decreased the larvae in the brains in group I and II (22.67 ± 5.41 and 37.17 ± 5.98) with no significant reduction in group III (130.5 ± 9.01). Histopathological examination of the liver from mice at four weeks p.i. in groups I and II revealed numerous granulomas, some of which contained degenerated larvae and the brain showed marked reduction in both the number of larvae and the extent of inflammatory reactions, whereas the findings in groups III were largely similar to those of the control group.