Diagnóstico coproparasitológico e avaliação da resistência anti-helmíntica da helmintose gastrintestinal em pequenos ruminantes

Abstract

Gastrointestinal helminthiasis in small ruminants, especially those caused by nematodes, are frequent and require treatment with anthelmintics. Some factors such as management, inadequate treatment and underdosage can lead to the development of anthelmintic resistance (AR), representing a global problem. The benzimidazole (BZ) class is one of the most widely used in the treatment of helminthiasis and consequently one of the most common with resistance problems. One of the parasites most associated with AR in small ruminants is Haemonchus contortus, which causes serious problems in the herd and can lead to the death of the animal. Therefore, the aim of this study was to perform the coproparasitological diagnosis of small ruminants and detect molecular markers associated with resistance to BZs in populations of gastrointestinal nematodes of small ruminants in the state of Pernambuco. Feces were collected from 73 goats and three sheep from three farms and analyzed using the FLOTAC parasitological technique to obtain eggs per gram of feces (EPG). In addition, the abomasum content of 40 sheep was collected for adult helminth screening. A pool of feces was collected per farm and stool culture was performed to obtain infective third-stage larvae (L3). Adult helminthes and L3 were subjected to DNA extraction and polymerase chain reaction (PCR) for species identification and confirmation. The resistance profile of these parasites was determined by PCR amplification for the beta-tubulin gene related to AR, followed by sequencing. As a result, in FLOTAC the overall average was 1,797 Strongyloidea eggs. In stool cultures, L3 of Haemonchus sp. were the most frequently found, followed by Trichostrongylus spp. In the collection of abomasal contents, 15/40 (37,5%) of the animals presented the nematode. The PCR result of L3 and adult helminths confirmed the presence of H. contortus. However, no point mutations associated with BZs were found in the codons that have already been reported in H. contortus. Knowledge of anthelmintic resistance in nematodes present in small ruminants is essential to mitigate the development and dissemination of resistant isolates in Pernambuco.