Frequency of benzimidazole resistance in Haemonchus contortus populations isolated from sheep and goats in Bangladesh.

Anthelmintic resistance against gastrointestinal nematodes especially H. contortus of sheep and goat is a global issue. To address the gravity and extension of AR in Bangladesh, genotyping of 160 adult H. contortus parasitesw ere performed to confirm benzimidazole resistance allele from different geographic zones of Bangladesh based on allele specific PCR (AS-PCR). The genotype frequencies were 9.4% for homozygous resistant (rr), 61.2% for heterozygous (rS) and 29.4% for homozygous susceptible (SS) among the selected areas. The allelic frequency of the mutation conferring resistance (r) ranged from 27.5% to 52.5% indicating substantial existence of benzimidazole resistance in H. contortus in small ruminant nematodes. Therefore, it can be concluded that genotyping the F200Y polymorphism can be used to monitor the resistance and thereby to enhance the control on the development of anthelmintic resistance against H. contortus in small ruminant nematodes.