Fasciola hepatica: A comparative survey of adult fluke resistance to triclabendazole, nitroxynil and closantel on selected upland and lowland sheep farms in Northern Ireland using faecal egg counting, coproantigen ELISA testing and fluke histology
Fasciola hepatica: A comparative survey of adult fluke resistance to triclabendazole, nitroxynil and closantel on selected upland and lowland sheep farms in Northern Ireland using faecal egg counting, coproantigen ELISA testing and fluke histology
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DOI：
10.1016/j.vetpar.2014.11.016
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发表时间：
2015-01-15
影响因子：
2.6
通讯作者：
Fahweather, I.
中科院分区：
文献类型：
--
作者：
Hanna, R. E. B.;McMahon, C.;Fahweather, I.
为了调查北方爱尔兰（NI）羊群中肝片吸虫成虫对杀片吸虫剂三氯苯达唑（TCBZ）的耐药性的发生率和分布，从3组20只羊中采集个体直肠粪便样品，在全省分布的13个管理良好的绵羊农场中，对动物进行TCBZ、硝苯腈或氯氰碘柳胺治疗后21天（给药前）和21天（给药后）的研究。使用粪便虫卵计数减少（FECRT）和F。肝粪抗原ELISA检测。在一定的羊群中，分别于TCBZ处理后3d和21 d处死2只粪卵数（FEC）高的羊，将吸虫生殖器官的组织学与未处理羊的吸虫和死前2d用硝苯腈或氯氰碘柳胺处理的羊的吸虫进行比较。使用苏木精和伊红（H&E）染色和原位杂交方法（TdT介导的dUDP缺口末端标记[TUNEL]）来证明细胞凋亡。FECRT的结果显示，在所有具有高吸虫负荷的鸡群中，TCBZ对治疗慢性肝片吸虫病无效，这一发现通常得到粪抗原减少试验（CRT）结果的支持。与未处理的吸虫相比，这些羊群中TCBZ处理的绵羊的吸虫生殖器官的组织学是正常的，这与FECRT和CRT结果一起表明，在所有具有高吸虫负担的羊群中可能诊断出TCBZ抗性。相比之下，硝苯腈和氯氰碘柳胺被认为是完全有效的对TCBZ耐药的吸虫在每个羊群轴承高慢性吸虫负担。在NI南部和东部的低地管理所有具有高吸虫负担和TCBZ抗性的鸡群。北部和西部的高地鸡群的吸虫负担较低，或者没有感染;而且粪便中的粪便浓度太低，无法进行有效的耐药性测试。该研究强调了TCBZ抗性在整个F中的高水平渗透。肝吸虫种群在集约化管理的绵羊生产领域的高水平的吸虫挑战。此外，它强调了对慢性肝片吸虫病采取先发制人的化疗行动的重要性，使用杀吸虫剂有效地对抗产卵的成虫吸虫，以最大限度地减少下一季羔羊作物的牧场污染。本研究还证实了使用几种互补的方法（FECRT; CRT;吸虫组织学;比较驱虫效力试验）来确认吸虫耐药性的诊断。(C)2014爱思唯尔有限公司版权所有。
In order to investigate the incidence and distribution of adult fluke resistance to the fasciolicide tricalbendazole (TCBZ) amongst populations of Fasciola hepatica in sheep flocks in Northern Ireland (NI), individual rectal faeces samples were collected from 3 groups of 20 sheep, before (pre-dose), and 21 days after (post-dose) treatment of the animals with TCBZ, nitroxynil or closantel, on each of 13 well-managed sheep farms distributed across the province. The efficacy of each flukicide was determined for each farm, using faecal egg count reduction (FECRT) and F. hepatica coproantigen ELISA testing. In certain flocks, 2 sheep with high pre-dose faecal egg counts (FEC) were killed 3 days and 21 days respectively after TCBZ treatment, and the histology of the fluke reproductive organs was compared with that of flukes from untreated sheep, and from sheep treated with nitroxynil or closantel 2 days prior to death, using haematoxylin and eosin (H&E) staining and an in situ hybridisation method (TdT-mediated dUDP nick end labelling [TUNEL]) to demonstrate apoptosis. Results from FECRT revealed that in all flocks with a high fluke burden, TCBZ was ineffective in treating chronic fasciolosis, and this finding was generally supported by the results of the coproantigen reduction test (CRT). The histology of reproductive organs of flukes from TCBZ-treated sheep in these flocks was normal, when compared with untreated flukes, and this, together with the FECRT and CRT findings, indicated a likely diagnosis of TCBZ resistance in all the flocks with a high fluke burden. In contrast, nitroxynil and closantel were found to be fully effective against TCBZ-resistant flukes in each of the flocks bearing a high chronic fluke burden. All of the flocks with a high fluke burden and TCBZ resistance were managed on lowland in the South and East of NI. Upland flocks, in the North and West, had low fluke burdens, or were clear of infection; and FECs were too low to allow valid resistance testing. The study highlights the high level of penetration of TCBZ resistance throughout F. hepatica populations in areas of intensively managed sheep production with a high level of fluke challenge. Further, it emphasises the importance of pre-emptive chemotherapeutic action against chronic fasciolosis, using flukicides effective against the egg-producing adult flukes to minimise pasture contamination for the next season's lamb crop. This study also exemplifies the use of several complementary methods (FECRT; CRT; fluke histology; comparative anthelmintic efficacy testing) for confirmation of a diagnosis of fluke drug resistance. (C) 2014 Elsevier B.V. All rights reserved.