Evaluation of the prevalence of Echinococcus multilocularis in dogs, and risk factors for infection, in southern Ontario

多房棘球绦虫(狐绦虫)是一种人畜共患寄生虫，如果不治疗，人的病死率很高。在北美，多房棘球绦虫成虫出现在郊狼和狐狸的小肠内。成熟时，卵从粪便中排出；如果被野生啮齿动物摄取，幼虫阶段在肝脏发育，导致泡状棘球绦虫病(AE)。当被感染的啮齿动物被野生犬类摄取时，生命周期就完成了。尽管北美野生动物的地理分布很广，但很少有狗或人感染的病例。此外，在2012年之前，安大略省还没有诊断出多房棘球绦虫。自那以后，安大略省南部的狗和非人类灵长类动物已经报告了7例AE病例。因此，最近对安大略省南部野生犬类中多房棘球绦虫的流行率进行了评估；23%的郊狼和狐狸被感染。此外，在与安大略湖西端金马蹄区(GHR)有关的10个公共卫生单位中发现了一个感染热点。由于这是一种新的、正在出现的对狗和人类健康的威胁，本研究的目的是确定(I)在GHR内没有牵引带的狗的多房棘球绦虫感染的流行率，并确定这些狗感染的危险因素，以及(Ii)同一地区的啮齿动物。第一个目标将通过收集500只狗的粪便样本来实现，这些狗参观了GHR的10个非皮带狗公园。另外50只狗将在位于感染热点内的六国保护区进行抽样。目标(Ii)将通过在同一公园内检查啮齿动物来解决。另一个目标是使用目前的金标准诊断试验和一种新的粪便抗原诊断方法来确定狗粪便中所有肠道寄生虫的流行率。所有粪便样本都将使用一种用于欧洲国家监测项目的分子方法进行多房埃希氏菌的分析。这一结果将有助于确定哪些狗应该预防治疗多房性埃希氏菌，从而降低传播给人的风险。该项目还将帮助验证一种新的兽医粪便寄生虫诊断测试的性能。

Echinococcus multilocularis (the fox tapeworm) is a zoonotic parasite that has a high case fatality rate in people when untreated. In North America, adult E. multilocularis occur in the small intestine of coyotes and foxes. When mature, eggs are shed in the feces; if ingested by wild rodents, the larval stage develops in the liver causing the disease alveolar echinococcosis (AE). The life cycle is completed when an infected rodent is ingested by wild canids. Despite a broad geographic distribution in wildlife in North America, very few infections have been described in dogs or people. Furthermore, prior to 2012, E. multilocularis had not been diagnosed in Ontario. Since then, seven cases of AE have been reported in dogs and non-human primates in southern Ontario. As a result, the prevalence of E. multilocularis was recently evaluated in wild canids across southern Ontario; 23% of coyotes and foxes were shown to be infected. In addition, an infection hot spot was identified in ten Public Health Units associated with the Golden Horseshoe region (GHR) at the western end of Lake Ontario. Since this is a new, emerging threat to dog and human health, the objectives of this study are to determine the prevalence of E. multilocularis infections in (i) off-leash dogs within the GHR, and to identify risk factors for infection in these dogs, and (ii) rodents in the same area. The first objective will be achieved by collecting fecal samples from 500 dogs visiting 10 off-leash dog parks in the GHR. An additional 50 dogs will be sampled in the Six Nations reserve situated within the infection hotspot. Objective (ii) will be addressed by examining rodents in the same parks. An additional objective is to determine the prevalence of all intestinal parasites in the feces of the dogs using the current gold standard diagnostic tests and a new fecal antigen diagnostic method. All fecal samples will be analysed for E. multilocularis using a molecular method that is used for national surveillance programs in Europe. The results will help determine which dogs should be treated preventively for E. multilocularis, thereby reducing the risk of transmission to people. The project will also help validate the performance of a new fecal parasite diagnostic test for veterinary practitioners.