Resistência anti-helmíntica de nematoides gastrointestinais em ovinos na região semiárida de Minas Gerais

Abstract

This study was carried out to detect an anthelmintic resistance to ivermectin, albendazole and levamisole in gastrointestinal nematodes of sheep in the properties of the Serra Geral microregion in the North of Minas Gerais. A total of 846 sheep of different ages and breeds belonging to 17 properties where the animals were not treated with anthelmintic in the previous 90 days. Amongst the properties where were collected the feces samples, in 12 were found animals with or equal to 200 eggs per gram of feces (EPG), totaling 38.42% of sheep in which anthelmintics were tested. The fecal egg count reduction test(FECRT) was performed from results gotten in EPG counts. The lower confidence limit (LCL 95%) was calculated for each property. It was determined the FECRT cutoff <95%, and the lower confidence limit (LCL) <90% was used as a more accurate evaluation of the results, confirming or not an anthelmintic resistance in gastrointestinal nematodes. When the percentage of FECRT and LCL were lower than designated cut-off points, anthelmintic resistance was confirmed. If the percentage of FECRT or LCL was below the cut-off point, resistance was suggested. When the LCL was not calculated, the FECRT was below the cut-off point, resistance was confirmed. In five of the 17 properties, the producers claimed not to carry out the vermifugation of the animals. In 41.18% of the properties ivermectin was used and in 17.65% albendazole was used, that justified because 33.3% of the properties in which a resistance was only suggested to levamisol. There was multiple resistance to tested bases. In just one propriety there was not multiple, presenting resistance only to albendazole. The Haemonchus sp. genus was the most prevalent before and after vermifugation.