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

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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.