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，未经治疗时致死率很高。在北美，成年的多房棘球绦虫出现在土狼和狐狸的小肠中。成熟后，卵随粪便排出；如果被野生啮齿动物摄入，幼虫期在肝脏发育，引起肺泡棘球蚴病（AE）。当被感染的啮齿动物被野生犬科动物吞食时，生命周期就结束了。尽管在北美野生动物中有广泛的地理分布，但很少有狗或人感染的报道。此外，在2012年之前，安大略省未诊断出多房性肠球菌。从那时起，在安大略省南部的狗和非人类灵长类动物中报告了7例AE病例。因此，最近在安大略省南部的野生犬科动物中评估了多房绦虫的流行情况；23%的土狼和狐狸被证明感染了。此外，在安大略湖西端与金马蹄地区（GHR）有关的10个公共卫生单位中确定了一个感染热点。由于这是对狗和人类健康的一种新出现的威胁，本研究的目的是确定(1)GHR内未拴绳的狗中多房肠杆菌感染的流行情况，并确定这些狗和(2)同一地区的啮齿动物感染的危险因素。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个不带皮带的狗公园。另外50只狗将在位于感染热点的六国保护区取样。目的（ii）将通过检查同一公园的啮齿动物来解决。另一个目标是利用目前的金标准诊断试验和一种新的粪便抗原诊断方法确定狗粪便中所有肠道寄生虫的患病率。将使用欧洲国家监测规划中使用的分子方法对所有粪便样本进行多房大肠杆菌分析。研究结果将有助于确定哪些狗应该接受多房肠杆菌的预防性治疗，从而降低传播给人类的风险。该项目还将帮助兽医验证一种新的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.