In vivo efficacy of levamisole against larval stages of Angiostrongylus cantonensis and A. costaricensis.

Anti-larval effects of levamisole were examined on A. cantonensis in rats and A. costaricensis in mice. 1) In rats inoculated with 40 infective larvae of A. cantonensis: Compared with a non-treated control group, a significant reduction in number of worms recovered was seen in the group receiving a single dose of 1.0 mg/kg or more. A significant decrease in host lung-body weight ratio was seen in the group receiving drug of 3.0 mg/kg or more. 2) In mice inoculated with 20 infective larvae of A. costaricensis. In the non-treated control group, a severe loss in body weight and death of host animals were observed. A single dose of 30 mg/kg on 3, 4 or 5 days post-infection remarkably inhibited these changes. At 30 mg/kg for 3 or 7 days levamisole was more effective than a single dose of the drug. These results suggest that levamisole has conspicuous in vivo effects against larval stages of A. costaricensis as well as A. cantonensis.