Anthelmintic effect of levamisole hydrochloride or ivermectin on tissue toxocariasis of mice

Paranatal transmission of Toxocara canis infection could be prevented in pups if an effective drug were administered to pregnant bitches. This drug also could eliminate the larvae in dogs that have been experimentally infected repeatedly to produce protective immunity. For these reasons, we assayed the effect of 2 doses of levamisole hydrochloride or ivermectin on T canis larvae. Mice (5 groups) were infected with 1,000 infective T canis larvae and then treated with 2 different dosages of levamisole hydrochloride (6 mg/kg or 12 mg/kg, given subcutaneously), 2 different dosages of ivermectin (0.2 mg/kg or 0.4 mg/kg, given IM) or 0.15M NaCl (given subcutaneously) once a day from days 15 to 28 of infection. On day 33 of infection, the parasites in liver, lungs, brain, and carcass were obtained and compared between groups. The smaller dosage of levamisole hydrochloride (6 mg/kg) significantly decreased only carcass parasitism to 17% of that in the controls, but did not affect significantly the total parasite load. The larger dosage of levamisole hydrochloride (12 mg/kg) decreased the infection in all organs, but particularly in carcass and brain; total parasitism was only 36% of that in the controls. The smaller dosage of ivermectin (0.2 mg/kg) significantly increased the number of larvae in the lungs to 550% of that in the controls, but it did not significantly affect the total parasite load. The larger dosage of ivermectin (0.4 mg/kg) significantly decreased only brain parasitism, but liver and total parasitism were decreased to 40% and 57%, respectively, compared with that in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)