Resistance to fenbendazole in Ascaridia dissimilis, an important nematode parasite of turkeys
Resistance to fenbendazole in Ascaridia dissimilis, an important nematode parasite of turkeys
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DOI：
10.3382/ps/pez379
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发表时间：
2019-11-01
期刊：
影响因子：
4.4
通讯作者：
Kaplan, Ray M.
中科院分区：
文献类型：
--
作者：
Collins, James B.;Jordan, Brian;Kaplan, Ray M.
家禽高效生产的一个重要因素是寄生虫的管理。蛔虫是火鸡最常见的小肠线虫寄生虫，高达100%的火鸡群被感染。高蠕虫负荷可引起坏死性肠炎，导致鸡群的高死亡率。最近，我们注意到多个案例，尽管频繁间隔施用驱虫剂，但屠宰时仍观察到高负荷，这表明A.异化为了解决这个问题，我们获得了A.从4个商业火鸡养殖场分离出的异长链霉菌，并进行了受控的效力试验以确定是否存在芬苯达唑抗性。三个农场有频繁使用芬苯达唑和在屠宰时发现的蠕虫的历史，这表明它们可能具有耐药性，一个是有机农场，除了几年前农场已经过渡到有机生产之外，我们没有其他历史。对于每种蠕虫分离株，有2个处理组和2个未处理组，每组含有9只鸡，所有组在2个单独的房间中重复。用约200个感染性蛋感染禽类，并且处理组从感染后第24天开始连续5天在水中接受芬苯达唑（SafeGuard Aquasol，lmg/kg）。最后一次给药后一周，对鸡进行尸检，收集肠内容物并计数蠕虫。四个分离株中有三个表现出大于99%的疗效，表明它们对芬苯达唑完全敏感。然而，第四个分离株显示出63.89%的显著降低的效力，表明存在耐药性。有趣的是，这是有机农场，而3个“疑似”耐药的农场都被证明是完全易感的。假设1个随机获得的A.在该研究中，在4个测试的dissimilis中，证明了耐药性，芬苯达唑耐药性可能是火鸡农场中比目前认识到的更大的问题。还需要进一步的研究来确定耐药性的普遍性，以及耐药性A。对火鸡生产的影响
An important factor in efficient production of poultry is management of parasites. Ascaridia dissimilis is the most prevalent small intestinal nematode parasite of turkeys with up to 100% of flocks infected. High worm burdens can cause necrotic enteritis leading to high mortality in flocks. Recently, we were made aware of multiple cases where high burdens were seen at slaughter despite the administration of anthelmintics at frequent intervals, suggesting that resistance may have evolved in A. dissimilis. To address this issue, we obtained eggs of A. dissimilis from 4 commercial turkey farms and performed controlled efficacy tests to determine if fenbendazole resistance was present. Three farms had histories of frequent use of fenbendazole and worms found at slaughter, suggesting they may have resistance, and one was an organic farm where we had no additional history other than the farm had transitioned to organic production a few years earlier. For each worm isolate there were 2 treated and 2 untreated groups containing 9 birds each, with all groups being replicated in 2 separate rooms. Birds were infected with approximately 200 infective eggs, and treated groups received fenbendazole in the water (SafeGuard Aquasol, 1 mg/kg) for 5 consecutive days starting on day 24 post-infection. One week after the last treatment birds were necropsied, intestinal contents were collected and worms enumerated. Three of the four isolates demonstrated greater than 99% efficacy, indicating they were fully susceptible to fenbendazole. However, the fourth isolate demonstrated a significantly reduced efficacy of 63.89%, indicating the presence of resistance. Interestingly, this was the organic farm, whereas the 3 farms with "suspected" resistance all turned out to be fully susceptible. Given that 1 randomly acquired isolate of A. dissimilis, out of 4 tested, demonstrated resistance in this study, fenbendazole resistance may be a much larger problem on turkey farms than is currently recognized. Additional studies are needed to determine the prevalence of resistance, as well as the economic impact that resistant A. dissimilis have on turkey production.