Antiparasitic Drug Efficacy and Resistance Monitoring for Haemonchus contortus in Small Ruminants in North West Nigeria

This study evaluates the therapeutic efficacy of commonly used anthelmintic drugs against Haemonchus contortus in small ruminants in North West Nigeria and screens for molecular resistance markers in recovered parasite populations. Haemonchus contortus is the most pathogenic and economically significant gastrointestinal nematode of sheep and goats in Nigeria, and evidence from other West African countries suggests that benzimidazole and levamisole resistance is emerging. Using a faecal egg count reduction test (FECRT) design, 240 naturally infected sheep and goats from 20 farms in Kano, Katsina, and Sokoto States were randomly allocated to treatment with albendazole, levamisole, ivermectin, and a negative control group. Pre-treatment and post-treatment (day 14) faecal egg counts were performed by the McMaster technique. FECRT-based resistance was suspected when egg count reduction was below 95 percent. Haemonchus contortus larvae from pre-treatment faecal cultures were subjected to isotype 1 beta-tubulin gene sequencing to detect SNPs associated with benzimidazole resistance. The study fills a critical gap in anthelmintic resistance data for North West Nigeria. Findings revealed albendazole FECRT reduction of 71 percent (indicating resistance), levamisole reduction of 84 percent (suspected resistance), and ivermectin reduction of 92 percent (susceptible). Beta-tubulin SNPs at codons 167, 198, and 200 associated with benzimidazole resistance were detected in 68 percent of sequenced larvae. The study recommends strategic drug rotation, refugia-based management, and introduction of targeted selective treatment protocols. Keywords: Haemonchus contortus, anthelmintic resistance, small ruminants, FECRT, North West Nigeria.