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Abstract：
Strongylus vulgaris is considered the most pathogenic nematode parasite of the horse. Frequent deworming programs since the 1970s have reduced the prevalence of S. vulgaris to low levels, but to the price of widespread benzimidazole resistance in the small strongyles (cyathostominae) and ivermectin resistance especially in the equine roundworm Parascaris spp. To slow down the progression of anthelmintic resistance in Sweden, horse anthelmintics were made prescription only medicine in 2007 and selective therapy principles were introduced. This means that only individuals with high egg excretion or clinical signs of helminth infection were treated instead of blanket treatment of all horses on a farm. The aims of this study were to investigate the prevalence and risk factors associated with S. vulgaris infection in Sweden ten years after the introduction of a selective therapy regime. A total of 529 faecal samples from 106 farms were collected during March to June in 2016 and 2017. A web-based questionnaire was used to collect information about deworming routines. Strongyle faecal egg counts (FEC) were performed by McMaster and presence of S. vulgaris was demonstrated with a specific PCR on individual larval cultures. Results were analysed by mixed logistic (S. vulgaris prevalence) or linear (FEC) regression models, where farm was included as random factor. The overall prevalence of S. vulgaris at individual and farm levels was 28% and 61%, respectively. We observed a 2.9 increased odds risk of S. vulgaris infection on farms that based their treatment on strongyle FEC only as compared to farms that complemented strongyle FECs with larval cultures or dewormed regularly, 1-4 times per year, without prior diagnosis. We found no association between the prevalence of S. vulgaris and strongyle FEC level, horse age, geographical region or signs of colic. The prevalence of S. vulgaris was 25% in horses shedding ≤150 eggs per gram. Thus horses with low strongyle FECs that are left untreated could be an important source of S. vulgaris infection. This may be an important reason for the approximately three-fold increase in S. vulgaris prevalence since 1999 in Sweden. However, our combined results indicate that selective therapy based on a combination of strongyle FECs and larval cultivation was not associated with an increased risk of S. vulgaris infection. Still, S. vulgaris needs to be monitored continuously and should be taken into careful consideration when the treatment frequency is reduced.
摘要：
寻常型线虫被认为是马的致病性最强的线虫寄生虫。自1970年代以来，频繁的驱虫计划已将普通链球菌的患病率降低到较低水平，但是，以小株（cyathostominae）和伊维菌素耐药性的广泛苯并咪唑耐药性为代价，尤其是在马蛔虫中。为了减缓瑞典驱虫药耐药性的发展，马驱虫药于2007年制成处方，并介绍了选择性治疗原则。这意味着仅对具有高卵排泄或蠕虫感染临床症状的个体进行治疗，而不是对农场中的所有马进行全面治疗。这项研究的目的是调查瑞典在引入选择性治疗方案十年后与寻常性链球菌感染相关的患病率和危险因素。在2016年和2017年3月至6月期间，共从106个农场收集了529个粪便样本。使用基于网络的问卷来收集有关驱虫程序的信息。McMaster进行了Strongyle粪便卵计数（FEC），并通过对单个幼虫培养物的特异性PCR证明了寻常性链球菌的存在。结果采用混合逻辑分析(S.寻常患病率)或线性(FEC)回归模型，其中农场被列为随机因素。普通链球菌在个体和农场水平的总体患病率为28%和61%，分别。我们观察到，与用幼虫培养或定期驱虫补充strongyleFECs的农场相比，基于strongyleFEC的农场的寻常型链球菌感染风险增加了2.9。每年1-4次,没有事先诊断。我们发现普通链球菌的患病率和强FEC水平之间没有关联，马龄,地理区域或绞痛的迹象。在每克脱落≤150个卵的马中，寻常性链球菌的患病率为25％。因此，未经治疗的低硬FECs马可能是寻常型链球菌感染的重要来源。这可能是瑞典自1999年以来寻常型链球菌患病率增加约三倍的重要原因。然而,我们的综合结果表明,基于强组织FECs和幼虫培养的组合的选择性治疗与寻常型链球菌感染风险的增加无关.尽管如此，S.vulgaris需要持续监测，当治疗频率降低时，应仔细考虑。
