Investigation of the prevalence of Echinococcus multilocularis, and risk of infection, in wild canids in Ontario, Canada

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狐狸和郊狼的小肠内。成熟时，卵从粪便中排出；如果被中间宿主(如野生啮齿动物)摄取，肝脏内会形成泡状包虫病。当中间宿主被野生犬科动物摄取时，生命周期就完成了。从历史上看，北美有两个公认的地方病流行地区：北部苔原地带和中北部地区，该地区包括加拿大三个省和美国13个毗邻的州。奇怪的是，尽管地理分布如此广泛，但很少有人在狗、猫或人身上描述多房性埃希氏菌的病例。在2012年前，安大略省从未诊断出多房埃希氏菌。然而，自那以后，安大略省南部报告了6例泡状棘球绦虫病；4例发生在狗身上，2例发生在非人类灵长类动物身上。其中五只动物没有离开安大略省南部。由于这是一种新的、正在出现的对犬和人类健康的威胁，本研究的目标是：(I)确定多房埃希菌在安大略省南部郊狼和狐狸中的流行率和地理分布，(Ii)确定与郊狼和狐狸感染多房埃希菌有关的风险因素，以及(Iii)确定该地区狗和人感染多房埃希菌的高风险地区。这些目标将通过在两年内收集386只郊狼和386只狐狸身体的粪便样本来实现。此后，瑞典将使用被认为是目前粪便中多房埃希氏菌最灵敏的诊断方法的聚合酶链式反应分析样本。利用空间分析技术，每个身体的诊断数据和地理原产地信息将被用来绘制安大略省南部狗和人类感染的风险地图。还将确定郊狼和狐狸感染多房棘球绦虫的危险因素。需要这些信息来确定整个区域的公共和动物健康风险。

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 foxes and coyotes. When mature, eggs are shed in the feces; if ingested by the intermediate host (e.g. wild rodents) an alveolar hydatid cyst develops in the liver. The life cycle is completed when the intermediate host is ingested by wild canids. Historically, there are two recognized endemic areas in North America; the Northern Tundra Zone, and the North Central Region that includes three Canadian provinces and 13 contiguous US states. Strangely, despite this broad geographic distribution, very few cases of E. multilocularis have been described in dogs, cats or people. Prior to 2012, E. multilocularis had never been diagnosed in Ontario. However, since then, six cases of alveolar echinococcosis have been reported in southern Ontario; four in dogs, two in non-human primates. Five of the animals had not travelled outside southern Ontario. Since this is a new, emerging threat to canine and human health, the objectives of this study are: (i) to determine the prevalence and geographic distribution of E. multilocularis in coyotes and foxes across southern Ontario, (ii) to identify risk factors associated with E. multilocularis infection in coyotes and foxes, and (iii) to identify high risk areas for infection in dogs and people in this region. These objectives will be accomplished through the collection of fecal samples from 386 coyote and 386 fox carcasses over 2 years. Thereafter, the samples will be analyzed in Sweden using a polymerase chain reaction assay considered the most sensitive diagnostic method for E. multilocularis in feces at the current time. Using spatial analysis techniques, the diagnostic data and information about the geographic place of origin of each carcass will be used to map the risk of infection for dogs and humans across southern Ontario. Risk factors for E. multilocularis infection in coyotes and foxes will also be determined. Such information is needed to determine public and animal health risks across this region.