Haemonchus contortus Susceptibility and Resistance to Anthelmintics in Naturally Infected Egyptian Sheep.

Purpose: Susceptibility and resistance of Haemonchus contortus to anthelmintic drugs, including ivermectin, levamisole, and albendazole in naturally infected sheep were investigated.

Methods: Three sets of assays were conducted to detect drug efficacy. Firstly, in vivo estimation of drug resistance to H.