Multiple-species resistance to avermectin anthelmintics on beef cattle farms in Georgia, USA

IF 2 2区农林科学 Q2 PARASITOLOGY

Veterinary parasitology Pub Date : 2025-03-01 DOI:10.1016/j.vetpar.2025.110435

Leonor Sicalo Gianchini , Kelsey L. Paras , Melissa M. George , Sue B. Howell , Bob Storey , Matthew J. Denwood , Ray M. Kaplan

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Abstract

Anthelmintic resistance (AR) in gastrointestinal nematodes (GIN) is a worldwide problem in all livestock production systems. Several prevalence studies performed internationally demonstrate that AR in cattle parasites is a growing problem; however, there are no published studies on prevalence in the United States (USA). In this study, we performed fecal egg count reduction tests (FECRT) on twelve cow-calf farms in Georgia, USA. On all farms the efficacy of eprinomectin pour-on (Eprinex®) and doramectin injectable (Dectomax®) was tested individually, as well as a combination treatment of doramectin injectable with oral fenbendazole (Safe-guard®). Fenbendazole was also tested individually on 7 farms, and long-acting eprinomectin (LongRange®) on one farm. FECRTs were performed, analyzed and interpreted following the 2023 WAAVP guidelines. Coprocultures were conducted to assess genus-specific efficacy. Overall, 100 % (12/12) and 75 % (9/12) of farms had resistance to at least one of the avermectin drugs tested in one or more GIN species, respectively. FECR ranged from 14.0 % to 96.8 % (mean=61.81 %) and 8.9–97.9 % (mean=66.87 %) for eprinomectin and doramectin, respectively; this difference was not significant (P = 0.924). In contrast, FECR for fenbendazole was high on all 7 farms tested, with just one farm demonstrating a low level of resistance. The combination treatment of doramectin plus fenbendazole was effective on all 12 farms (mean FECR=98.75 %), being significantly higher than for eprinomectin or doramectin (P≤0.001). Where coproculture data were sufficient to evaluate genus-specific reduction, resistance to Cooperia spp., Haemonchus spp. and Ostertagia spp. was present on 11/12 (92 %), 6/8 (75 %), and 4/10 farms (40 %), respectively. These data demonstrate that resistance to avermectin drugs is highly prevalent in Cooperia, Haemonchus, and Ostertagia on beef farms in Georgia. Though these data represent just one southern state, given the high level of movement of cattle in the USA, AR in GIN of cattle is likely to be highly prevalent throughout not only the southern USA, but across much of the country.

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美国乔治亚州肉牛农场对阿维菌素抗虫药的多物种耐药性

胃肠线虫（GIN）的抗虫性（AR）是所有畜牧生产系统中的一个世界性问题。在国际上进行的几项流行病学研究表明，牛寄生虫中的急性呼吸道感染是一个日益严重的问题；然而，没有关于美国流行率的公开研究。在这项研究中，我们在美国乔治亚州的12个牛场进行了粪蛋计数减少试验（FECRT）。在所有农场，分别测试了依普诺菌素（Eprinex®）和多拉菌素注射剂（Dectomax®）的疗效，以及口服芬苯达唑（Safe-guard®）联合治疗的多拉菌素注射剂。在7个农场单独测试了芬苯达唑，在一个农场测试了长效依普诺菌素（LongRange®）。fecrt按照2023 WAAVP指南进行分析和解释。进行共培养以评估属特异性功效。总体而言，100 %（12/12）和75 %（9/12）的养殖场分别对一种或多种GIN品种的至少一种阿维菌素药物耐药。依普诺米素和多拉菌素的FECR分别为14.0 % ~ 96.8% %（平均61.81 %）和8.9 ~ 97.9% %（平均66.87 %）；差异无统计学意义（P = 0.924）。相比之下，在所有接受检测的7个农场中，芬苯达唑的FECR都很高，只有一个农场显示出低水平的耐药性。doramectin + fenendazole联合用药对12个养殖场均有效（平均FECR=98.75 %），显著高于eprinomectin或doramectin （P≤0.001）。在共养数据足以评估种特异性减少情况的养殖场中，分别有11/12（92 %）、6/8（75 %）和4/10（40 %）养殖场对库伯氏蝇、Haemonchus和Ostertagia产生抗性。这些数据表明，对阿维菌素药物的耐药性在乔治亚州肉牛养殖场的库伯虫、Haemonchus和Ostertagia中非常普遍。虽然这些数据仅代表一个南部州，但考虑到美国牛的高水平流动，牛的GIN中的AR可能不仅在美国南部，而且在全国大部分地区都非常普遍。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Veterinary parasitology 农林科学-寄生虫学

CiteScore

5.30

自引率

7.70%

发文量

126

审稿时长

36 days

期刊介绍： The journal Veterinary Parasitology has an open access mirror journal,Veterinary Parasitology: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review. This journal is concerned with those aspects of helminthology, protozoology and entomology which are of interest to animal health investigators, veterinary practitioners and others with a special interest in parasitology. Papers of the highest quality dealing with all aspects of disease prevention, pathology, treatment, epidemiology, and control of parasites in all domesticated animals, fall within the scope of the journal. Papers of geographically limited (local) interest which are not of interest to an international audience will not be accepted. Authors who submit papers based on local data will need to indicate why their paper is relevant to a broader readership. Parasitological studies on laboratory animals fall within the scope of the journal only if they provide a reasonably close model of a disease of domestic animals. Additionally the journal will consider papers relating to wildlife species where they may act as disease reservoirs to domestic animals, or as a zoonotic reservoir. Case studies considered to be unique or of specific interest to the journal, will also be considered on occasions at the Editors'' discretion. Papers dealing exclusively with the taxonomy of parasites do not fall within the scope of the journal.