Resistência anti-helmíntica em nematódeos gastrintestinais de pequenos ruminantes no Estado de Pernambuco

Abstract

The sheep and goat farming suffer great economic losses due to parasitism by gastrointestinal nematodes, reaching derail this exploration in some regions. The control of such parasites is done primarily with the use of anthelmintic drugs. The inefficiency of this type of control are the first signs of anthelmintic resistance appearance (AR), which constitutes one of the main negative and limiting factors for animal production, since it prevents the effective control of helminths in small ruminants, with adverse consequences on production rates. The anthelmintic resistance in nematodes of small ruminants for the three groups most commonly used drugs: benzimidazole (BZs) imidazotiazóis (LEV) and macrocyclic lactones (MLs) has been reported and have grown rapidly in different regions of the world. The efficient control of these parasites and the early diagnosis of anthelmintic resistance, especially in Haemonchus contortus should be recommended in order to economically viable sheep and goat breeding. Knowledge of various genetic aspects of this phenomenon can increase the shelf life of drugs currently used, and therefore try to preserve the susceptibility of parasites. This work has the objective of diagnosing anthelmintic resistance in properties of sheep and goats and to analyze the relationship with the management of the properties and identify the presence of DNA responsible for anthelmintic resistance in helminth populations of small ruminants in the state of Pernambuco. The methodological procedures were approved by the Ethics Committee on Animal Use - CEUA - UFRPE. Samples from adult specimens of H. contortus were obtained from animals naturally infected with gastrointestinal helminths belonging to properties located in the cities of the state of Pernambuco: Sairé (Agreste), Recife (Metropolitan Region), Bonito (Agreste), Moreno (Metropolitan Region) Gameleira (South Forest), Camocim de São Félix (Agreste), Serra Talhada (Sertão). The properties of Recife and Bonito created only goats and the others only sheep. For PCR, samples from adult specimens of H. contortus were obtained from animals naturally infected with gastrointestinal helminths, which were stored in Eppendorf tubes with PBS at 4 ° C, identified and sexed in Parasitic Diseases Laboratory of Domestic Animals - UFRPE. It was performed a pool of 20 adult males of H. contortus from each property for the extraction of DNA. The extracted DNA samples were analyzed in Parasitic Diseases Laboratory at the Federal University of Parana. PCR in order to amplify gene fragments encoding 1 isotype of β-tubulin which held the sequence of codon 200 was performed;it was also performing a PCR to identify the species of helminths collected. Both amplification reactions were performed in a thermocycler Veriti Life gradient. A sample of 20 uL of each reaction was analyzed on a 0.8% agarose gel and visualized under UV light. PCR products were purified with the commercial PureLink® Quick Gel Extraction Kit (Invitrogen, USA) and sequenced by capillary electrophoresis (Sanger method) using the ABI3130 platform (Life Technologies, USA). Anthelmintic efficacy by "in vivo" method was also evaluated the by means of Fecal Egg Counting Reduction Test (FECRT) using the formula:% efficacy = [(mean OPGpre-treatment - average OPGpost-treatment) / average OPGpre-treatment)] x 100. It was detected DNA responsible for anthelmintic benzimidazole resistance (BZ) in all the evaluated properties. The percentage of anthelmintic efficacy for moxidectin presented as effective only seven days after treatment. Several management failures of control of gastrointestinal helminths were found. The results obtained confirm the anthelmintic benzimidazole resistance in H. contortus goats and sheep in the state of Pernambuco - Brazil, becoming the first record of molecular diagnosis of RA in ruminants in the State. also characterize the decline of the anthelmintic efficacy of moxidectin in herds. Both situations are favored by inadequate management practices and indiscriminate use of chemicals for the control of gastrointestinal helminths.