在澳大利亚的羊驼中首次发现捻转血矛线虫对驱虫药的耐药性。
First report of anthelmintic resistance in Haemonchus contortus in alpacas in Australia.
机构信息
Faculty of Veterinary Science, The University of Melbourne, Werribee, VIC 3030, Australia.
出版信息
Parasit Vectors. 2013 Aug 22;6(1):243. doi: 10.1186/1756-3305-6-243.
BACKGROUND
Parasitic nematodes can cause substantial clinical and subclinical problems in alpacas and anthelmintics are regularly used to control parasitic nematodes in alpacas. Although anthelmintic resistance has been reported in ruminants worldwide, very little is known about anthelmintic resistance in alpacas. The present study was carried out to confirm a suspected case of anthelmintic resistance in Haemonchus contortus in alpacas in Australia.
METHODS
Post mortem examination of an alpaca was conducted to determine the cause of its death. To confirm a suspected case of macrocyclic lactone (ML) resistance in H. contortus in alpacas, a faecal egg count reduction test (FECRT) was performed using closantel (7.5 mg/kg) and ivermectin (0.2 mg/kg). Nematode species were identified by morphological and molecular methods.
RESULTS
Post mortem examination of a 1-year-old female alpaca that had died following a brief period of lethargy, anorexia and recumbency revealed severe anaemia, hypoproteinaemia and gastric parasitism by adult Haemonchus contortus, despite recent abamectin (0.2 mg/kg) treatment. Based on these findings and the exclusive use of MLs in the herd over the preceding six years, ML resistance in parasitic nematodes of alpacas on this farm was suspected. FECRT revealed that the efficacy of closantel was 99% (95% CI 93-100), whereas that of ivermectin was 35% (95% CI 0-78), indicating that the treatment failure was likely due to the presence of ML-resistant nematodes. Larval culture of faecal samples collected following ivermectin treatment consisted of 99% H. contortus and 1% Cooperia oncophora, a result confirmed using a PCR assay.
CONCLUSIONS
This study provides the first evidence of ML resistance in H. contortus in alpacas in Australia. Based on the extent of anthelmintic resistance in sheep gastrointestinal nematodes in Australia, veterinarians and alpaca owners should be encouraged to implement integrated parasite management strategies to improve nematode control in alpacas.
背景
寄生线虫会给羊驼带来严重的临床和亚临床问题，因此经常使用驱虫药来控制羊驼体内的寄生线虫。尽管全世界的反刍动物都有报道抗寄生虫药物耐药性，但关于羊驼的抗寄生虫药物耐药性却知之甚少。本研究旨在确认澳大利亚羊驼中疑似的旋毛虫耐药病例。
方法
对一只死亡的羊驼进行剖检，以确定其死亡原因。为了确认澳大利亚羊驼中疑似的大环内酯类（ML）抗药性旋毛虫病例，使用氯氰碘柳胺（7.5mg/kg）和伊维菌素（0.2mg/kg）进行粪便卵计数减少试验（FECRT）。通过形态学和分子方法鉴定线虫种类。
结果
对一只 1 岁雌性羊驼进行剖检，该羊驼在短暂的昏睡、食欲不振和卧地不起后死亡，发现其严重贫血、低蛋白血症和胃寄生有成熟的旋毛虫，尽管最近使用了阿维菌素（0.2mg/kg）进行了治疗。基于这些发现以及在过去六年中该羊群中仅使用 MLs 的情况，怀疑该农场的羊驼寄生线虫对 ML 产生了耐药性。FECRT 显示氯氰碘柳胺的疗效为 99%（95%CI 93-100），而伊维菌素的疗效为 35%（95%CI 0-78），这表明治疗失败可能是由于存在 ML 耐药线虫。伊维菌素治疗后采集的粪便样本进行幼虫培养，结果为 99%的旋毛虫和 1%的细颈线虫，这一结果通过 PCR 检测得到证实。
结论
本研究首次提供了澳大利亚羊驼中旋毛虫对 ML 耐药的证据。根据澳大利亚绵羊胃肠道线虫的抗寄生虫药物耐药程度，应鼓励兽医和羊驼所有者实施综合寄生虫管理策略，以改善羊驼的线虫控制。
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