Department of Biomedical Science and Veterinary Public Health, Parasitology Unit, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
Department of Biomedical Science and Veterinary Public Health, Parasitology Unit, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
Int J Parasitol Drugs Drug Resist. 2023 Dec;23:78-86. doi: 10.1016/j.ijpddr.2023.11.003. Epub 2023 Nov 14.
Consisting of approximately 50 different species, the cyathostomin parasites are ubiquitous in grazing horses. Co-infection with several species is common, and large burdens can cause the fatal disease of larval cyathostominosis. Due to intense anthelmintic drug use, cyathostomin resistance has developed to all available anthelmintic drug groups. Resistance to the anthelmintic drug pyrantel (PYR) has been documented in over 90% of studies published over the past two decades. In Sweden, a study performed in the early 2000s only confirmed resistance in 4.5% of farms. Further, prescription-only administration of equine anthelmintic drugs was enforced in Sweden in 2007. However, it is unknown if this conservative drug use has maintained PYR efficacy in cyathostomins. The aim of the present study was to investigate the effect of PYR on cyathostomin infection in Sweden using fecal egg count reduction tests (FECRTs). Further, the effect of PYR treatment on cyathostomin species composition was studied using metabarcoding. Sixteen farms with at least six horses excreting a minimum of 100 eggs per gram feces were included. Using the current World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines, PYR resistance was demonstrated in nine of farms, with seven farms showing full susceptibility. Farms with low biosecurity measures had significantly lower efficacy of PYR treatment. The most common cyathostomin species were Cylicocyclus nassatus, Cyathostomum catinatum, Cylicostephanus longibursatus, Cys. calicatus, Cys. goldi, Cys. minutus, Coronocyclus coronatus and Cya. pateratum, accounting for 97% of all sequence reads prior to treatment. Of these, Cyc. nassatus and Cya. catinatum had the highest occurrence, accounting for 68% of all sequence reads prior to PYR treatment. Treatment did not significantly affect the species composition. The results highlight the importance of drug efficacy testing when using PYR to treat cyathostomin infection, even when selective anthelmintic treatment and thus low treatment intensity, is used on the farm.
包含约 50 个不同物种的Cyathostomin 寄生虫在放牧马中无处不在。多种物种的共同感染很常见，大量感染会导致幼虫 Cyathostominosis 这种致命疾病。由于强烈使用驱虫药物，Cyathostomin 对所有现有驱虫药物组都产生了耐药性。在过去二十年发表的研究中，超过 90%的研究都记录了对驱虫药物吡喹酮（PYR）的耐药性。在瑞典，21 世纪初进行的一项研究仅在 4.5%的农场中确认了耐药性。此外，2007 年瑞典开始强制规定仅处方使用马用驱虫药物。然而，目前尚不清楚这种保守的药物使用是否维持了 PYR 在 Cyathostomin 中的疗效。本研究旨在使用粪便虫卵减少试验（FECRT）调查 PYR 对瑞典 Cyathostomin 感染的影响。此外，还使用代谢条形码研究了 PYR 治疗对 Cyathostomin 物种组成的影响。纳入了 16 个至少有 6 匹马的农场，这些马每克粪便至少排出 100 个虫卵。根据当前的世界兽医寄生虫学协会（WAAVP）指南，有 9 个农场表现出 PYR 耐药性，7 个农场表现出完全敏感性。生物安全措施较低的农场，PYR 治疗的效果明显较低。最常见的 Cyathostomin 物种是 Cylicocyclus nassatus、Cyathostomum catinatum、Cylicostephanus longibursatus、Cys. calicatus、Cys. goldi、Cys. minutus、Coronocyclus coronatus 和 Cya. pateratum，这些物种在治疗前占所有测序reads 的 97%。其中，Cyc. nassatus 和 Cya. catinatum 的出现频率最高，占 PYR 治疗前所有测序reads 的 68%。治疗并没有显著影响物种组成。研究结果强调了在使用 PYR 治疗 Cyathostomin 感染时进行药物疗效测试的重要性，即使在农场中使用选择性驱虫药物（因此治疗强度较低）也是如此。
