Anthelmintic resistance in gastrointestinal nematodes of cattle owned by smallholders in Southern Chile

IF 1.4 Q3 PARASITOLOGY
D. Tapia-Escárate, J. Paredes, J. Sanhueza
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Abstract

Helminth infections present a significant challenge to rural and indigenous smallholders. In a municipality of Los Lagos Region, Chile, ivermectin has been the preferred method of anthelmintic control in cattle, but its efficacy against gastrointestinal nematodes after years of usage had not been evaluated. In the spring of 2021, 30 smallholder cattle farmers and 128 bovines were selected using a one stage cluster sampling. During the first visit, fecal samples were collected, and animals were treated with subcutaneous ivermectin (0.2 mg/kg). Samples were sent to the Parasitology Laboratory of the Universidad Católica de Temuco. Fourteen days after the first sampling, a second fecal sample was taken from the same animals. Fecal eggs count (FEC) was performed in a Whitlock universal chamber. Animals with initial FECs ≤100 eggs per gram (epg) were excluded from the FEC reduction test (FECRT). The classification of resistance, suspected resistance, or susceptibility was established based on the guidelines provided by Denwood et al. (2023) and the WAAVP (2023). Among the 128 animals sampled and treated in the first sampling, 61 (47.7 %) had FEC ≥100 epg, with 85.2 % being ≤18-month-old. Considering animals with initial FEC ≥100, the mean farm adjusted FECR percentage was 55.0 % (95 % CI 34.3 % - 87.9 %) and the treatment failed to reduce the egg count per gram by more than 95 % in 65.6 % of the animals sampled. Additionally, animals ≥18-month-old had 48 times higher odds of achieving a 95 % FECR percentage than animals <6 month-old. This study provides evidence of gastrointestinal nematode's resistance to subcutaneous ivermectin treatment in smallholders' cattle in a municipality of Los Lagos region, Chile.
智利南部小农饲养的牛胃肠道线虫的抗虫性
寄生虫感染对农村和土著小农构成重大挑战。在智利洛斯拉各斯地区的一个自治市,伊维菌素一直是控制牛驱虫的首选方法,但其使用多年后对胃肠道线虫的效果尚未得到评估。2021年春季,采用单阶段整群抽样方法选择了30名小农和128头牛。在第一次访问时,收集粪便样本,并用皮下伊维菌素(0.2 mg/kg)治疗动物。样本被送到Católica de Temuco大学的寄生虫学实验室。在第一次取样14天后,从同一只动物身上采集了第二次粪便样本。在惠特洛克万能箱中进行粪卵计数(FEC)。初始FEC≤100个/克(epg)的动物被排除在FEC降低试验(FECRT)之外。根据Denwood等人(2023)和WAAVP(2023)提供的指南,确定了耐药、疑似耐药或易感性的分类。在第一次采样和处理的128只动物中,61只(47.7%)FEC≥100 epg, 85.2%≤18月龄。对于初始FEC≥100的动物,平均农场调整后的FECR百分比为55.0% (95% CI 34.3% - 87.9%), 65.6%的动物取样处理未能将每克卵数减少95%以上。此外,≥18月龄的动物达到95% FECR百分比的几率是6月龄动物的48倍。本研究提供了智利洛斯拉各斯地区小农牛中胃肠道线虫对皮下伊维菌素治疗耐药的证据。
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来源期刊
CiteScore
2.90
自引率
7.10%
发文量
126
审稿时长
97 days
期刊介绍: Veterinary Parasitology: Regional Studies and Reports focuses on aspects of veterinary parasitology that are of regional concern, which is especially important in this era of climate change and the rapid and often unconstrained travel of people and animals. Relative to regions, this journal will accept papers of the highest quality dealing with all aspects of disease prevention, pathology, treatment, epidemiology, and control of parasites within the field of veterinary medicine. Also, case reports will be considered as they add to information related to local disease and its control; such papers must be concise and represent appropriate medical intervention. Papers on veterinary parasitology from wildlife species are acceptable, but only if they relate to the practice of veterinary medicine. Studies on vector-borne bacterial and viral agents are suitable, but only if the paper deals with vector transmission of these organisms to domesticated animals. Studies dealing with parasite control by means of natural products, both in vivo and in vitro, are more suited for one of the many journals that now specialize in papers of this type. However, due to the regional nature of much of this research, submissions may be considered based upon a case being made by the author(s) to the Editor. Circumstances relating to animal experimentation must meet the International Guiding Principles for Biomedical Research Involving Animals as issued by the Council for International Organizations of Medical Sciences (obtainable from: Executive Secretary C.I.O.M.S., c/o W.H.O., Via Appia, CH-1211 Geneva 27, Switzerland).
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