Comparative Evaluation of Two In Vitro Tests for Detection of Ivermectin Resistance in Haemonchus contortus of Small...

Resistance against ivermectin in India has been detected solely implementing in vivo tests and there is no published report of resistance employing in vitro methods. The present study was carried out to study ivermectin resistance in H. contortus of small ruminants by two in vitro tests and to determine their efficacy in effectively detecting ivermectin resistance in the field isolates.

The present study was carried out in the small ruminant farms of the western region of Uttar Pradesh, India. Faecal samples with high egg per gram of faeces for H. contortus were selected. Two in vitro tests namely Micro agar larval development test and larval development assay were performed for assessing ivermectin resistance in field isolates of H. contortus by subjecting the eggs to different concentrations of ivermectin aglycone.

The results of the two in vitro tests implicated towards the susceptibility of H. contortus isolates in the area under study. The standard deviations of the two tests was compared and was found to be statistically non-significant.

It can be said that both in vitro tests are reliable for detecting resistance against different anthelmintics including ivermectin.