PDF(Pubmed)
Abstract：
Haemonchus contortus and Trichostrongylus colubriformis are the most important gastrointestinal nematodes causing serious losses in sheep production of tropical and subtropical regions. Prophylaxis of gastrointestinal nematode infections is based on anthelmintics use, but their frequent administration selects multiple-resistant parasites. To evaluate how the situation has changed over the last decades, the anthelmintic resistance status of gastrointestinal nematodes in sheep flocks was assessed in the current study and compared to previous surveys. In each one of the 15 flocks evaluated, animals (n ≥ 7) were allocated into at least five groups and treated as follows: 1) untreated control; 2) albendazole; 3) levamisole; 4) ivermectin; and 5) monepantel. If more animals were available, two additional groups were included: 6) closantel, and 7) moxidectin. The faecal egg count reduction test (FECRT) was carried out to evaluate the pre- and post-treatment using the SHINY tool. Haemonchus spp. was the most prevalent nematode from faecal cultures. The mean efficacy of albendazole was 40%. Only in two farms, levamisole presented a relatively high percentage of reduction in the FECRT about 90%, while ivermectin and moxidectin presented the worst mean efficacy of 34% and 21% among all farms, respectively. Like other anthelmintics, closantel demonstrated low efficacy (63%) across all farms evaluated. Monepantel presented an overall mean efficacy of 79%, but it was the only anthelmintic that presented efficacy ≥95%, in five farms. The results revealed that gastrointestinal nematodes with multiple anthelmintic resistance were prevalent in all 15 sheep herds. The research suggests that nematodes are becoming more and more resistant to various anthelmintic compounds, which has made the problem worse. This circumstance highlights the necessity to put into practice sustainable and long-lasting methods to prevent gastrointestinal nematode infections in sheep husbandry.
摘要：
扭曲血球和毛线菌是最重要的胃肠道线虫，在热带和亚热带地区的绵羊生产中造成严重损失。胃肠道线虫感染的预防是基于驱虫药的使用，但是他们的频繁施用选择了具有多重抗性的寄生虫。为了评估过去几十年来形势的变化，本研究评估了绵羊群中胃肠道线虫的驱虫抗性状况，并与以前的调查进行了比较。在评估的15群中的每一群中，将动物（n≥7）分为至少五组，并按以下方法治疗：1）未经治疗的对照组；2）阿苯达唑；3）左旋咪唑；4）伊维菌素；和5）monepantel。如果有更多的动物,包括另外两组：6）克洛桑特尔，和7)莫西丁。使用SHINY工具进行粪便卵数减少试验(FECRT)以评估治疗前和后处理。Haemonchusspp.是粪便培养物中最普遍的线虫。阿苯达唑的平均疗效为40%。只有两个农场,左旋咪唑在FECRT中表现出相对较高的减少百分比，约为90％，虽然伊维菌素和莫西丁在所有农场中表现出最差的平均疗效，分别为34%和21%，分别。像其他驱虫药一样，克洛桑特尔在所有被评估的农场中表现出低效率(63%)。Monepantel的总体平均疗效为79%，但它是唯一一种疗效≥95%的驱虫药，在五个农场结果表明，具有多种驱虫抗性的胃肠道线虫在所有15只绵羊群中普遍存在。研究表明，线虫对各种驱虫化合物的抵抗力越来越强，这使得问题变得更糟。这种情况凸显了在绵羊饲养中实施可持续和持久的方法以预防胃肠道线虫感染的必要性。
