Resistance of gastrointestinal nematoids of goats and sheep to the antihelmintics levamisol, ivermectin and albendazole

Abstract The aim of this study was to determine the resistance of gastrointestinal nematodes in goats and sheep to the anthelmintic drugs levamisole, ivermectin, and albendazole in the metropolitan region of São Luís Island, Maranhão, Brazil. Fecal samples were collected from 150 animals across four different farms; two farms had goats, and the other two had sheep. The samples were then randomly divided into three to four groups of 10 animals: Group I: control, without treatment; Group II: ivermectin treatment; Group III: levamisole treatment; and Group IV: albendazole treatment. Stool samples were collected from the rectal ampulla one day before treatment and 10 days after anthelmintic treatment. Individual coproparasitological examinations were performed using the modified McMaster technique at the Animal Health Laboratory of the Federal Institute of Maranhão, Campus São Luís-Maracanã. The efficacies of the anthelmintic drugs against gastrointestinal nematodes in goats and sheep were: 14.28%, and 13.6% for ivermectin; 0% and 79.4% for levamisole; and 59.8% and 3.43% for albendazole, respectively Gastrointestinal nematodes demonstrated multiple anthelmintic resistance, as the percentage reduction in egg count was less than 95% and the lower limit of the confidence interval was less than 90%.