Ex-vivo efficacy of commercially available anthelmintics against blood feeding stomach worm Haemonchus contortus of ruminants.

Abstract

Haemonchus contortus is the most prevalent and pathogenic gastrointestinal nematodes (GINs) in ruminants causing extensive economic losses. It is essential to estimate the efficacy of common commercially available anthelmintics against Haemonchus contortus parasite. Here, we standardized an ex-vivo culture platform for H. contortus and evaluated the efficacy of commonly used anthelmintics namely, albendazole (ABZ), levamisole (LVM), ivermectin (IVM), closantel (CLS) and rafoxanide (RFX). Adult worms were collected from abomasa of slaughtered animals, cultured in MEM, DMEM, M199 or RPMI with or without 20% FBS for up to 72h. Cultured worms were incubated with ABZ, LVM, IVM, RFX or CLS in DMEM supplemented with 20% FBS at different concentrations (0.5-50µg/ml) in triplicates and examined at 0, 3, 6, 12, 24, 36 and 48h post treatment. Of the culture conditions, DMEM supplemented with 20% FBS supported the survival of H. contortus for (P < 0.001) longer period of time which was used in the evaluation of anthelmintics. The efficacy of CLS and RFX were significantly (P < 0.001) higher than other drugs and 100% mortality was observed at 2µg/ml of CLS and RFX within 12h post treatment. However, ABZ, LVM, and IVM showed significant effect at the concentration of 50µg/ml with 48, 36, and 24h, respectively. Morphological changes included severe cuticle disruption around the buccal cavity, posterior region and vulva as well as loss of cuticle structure integrity coupled with expulsion and fragmentation of digestive components of parasites when treated with 50µg/ml of ABZ, LVM, and IVM and 2µg/ml of RFX and CLS. Collectively, DMEM supplemented with 20% FBS can be used as ex-vivo culture platform for maintenance of H. contortus, and RFX and CLS can be used as the promising drugs for the prevention, control and treatment of H. contortus infections.