Potentially fatal tapeworm spread by foxes, coyotes discovered in Ontario

Research from the University of Guelph has found that a quarter of foxes and coyotes in southern Ontariohave a tapeworm that can befatal to dogs andtheir owners.

Nearly one in four coyotes and foxes in the area from Windsor to Ottawatested positive forthe Echinococcus multilocularis tapeworm, which has only been found in Western Canada so far.

Prof. Andrew Peregrine, the report's lead researcher at the Ontario Veterinary College at the University of Guelph, said the findings suggestthe tapeworm is now well established and has been present even longer than indicated by the study.

Over two winters, the research team collected the carcasses of 460 foxes and coyotes, which belong to the wild canid family, and examined their intestines. They found 23 per cent of them tested positive for E. multilocularis. The first case was identified in 2012 in five dogs, as well as three other species in southern Ontario.

"In fact, when we first showed the data to those we were working with in Sweden, they said two things: You've had it a lot longer than you think, and it's most likely come in from the U.S.," Peregrine said.

The E. multilocularisparasite is spread by coyotes and foxes that eat infected rodents, such as field mice, the report found. For reasons that are not yet known, the wild animals don't become sick, but dogs that eat coyote or fox feces containingparasite eggsor dogs that hunt and eat infected rodentscan develop a severe infection called alveolar echinococcosis, or AE.

Humans can become infected immediately if these eggs find a way into their system. Pet owners are likely to acquire them from their dogs, not from direct contact with the poop of foxes and coyotes, Peregrine said. It's when owners let their pets sleep in their beds that they're more likely to get the microscopic tapeworm:If a dog's lower end is covered with theparasites, they can be transferred to the dog owner's bed and ingested that way.

The parasite goes largely undetected and can produce no signs or symptoms in dogs or humans. Both can carry the infection for years, but, over time, it aggressively attacks the liver, becoming potentially fatal.

If your dog is known to eat rodents, or hunt, there is a drug [itcan take] to stop itfrom developing intestinal infections.- Prof. Andrew Peregrine,University of Guelph

For dog owners, theinfection can cause devastating loss.

Megan MacLusky often let her dog Bauer off-leash during their walks in the fields and woods aroundGuelph, Ont., where she lives, and thetwotravelled to Alberta in 2012.

Two years later, Bauer developed a large masson his side, which turned out to be an enlarged liver and a cyst. After a series of testsand vet visits, hisveterinarian concluded that the liver was enlarged due to the AE infection, and the cyst contained the parasites.

MacLuskyput Baueron antiparasitic medication. When that didn't work, he underwent surgery, but the cyst could not be fully removed.

"Bauer actually went almost back to normal for about a year, but, eventually, more cysts formed," she said.

MacLusky said another surgery was performed in early 2016 to try to remove the cysts, but they had enveloped Bauer'sgallbladder and formed on other organs. Shortly after the operation, she made the difficult decision to put him down because he was in too much pain.

Preventive treatment

Peregrine says the parasite is present in both rural and urban areas, and it'simportant for dog owners to talk to their veterinarians about their pets' exercise habits.

"The vets now know where this parasite is, and where in the province the greatest risk is," he said.

"If your dog is known to eat rodents, or hunt, there is a drug [itcan take]to stop it from developing intestinal infections, sothat eliminates any concerns about infections in people in thehousehold."

But not every dog needs the treatment. If your dog never goes off-leash, either in an urban or rural area, it's unlikely to be eating rodents. The risk is higher for dogs who are often off-leash, Peregrine said.

'The European strain is known to be very virulent in people'

Alessandro Massolo, an adjunct professor of wildlife health ecology at the University of Calgary, has also researched the E. multilocularistapeworm. He says the extent of the threat in Ontario is still largely unknown, but it should be taken seriously, especially if itturns out to be a European strain, which is more dangerous than the North American one.

While the North American strain has been detected in Western Canada, the study of infected fox and coyote carcasses in southern Ontario did not establish which strain was present.

"If the European strain [is] circulating in our wildlife, then things change completely, because the European strain is known to be very virulent in people," Massolo said.

If the European is present in Ontario, it's not yet known how it arrived.

Nor can the geographic range of the parasite be fully understood until a proper survey is done, but such surveystake a long time and tend to be costly, he said.

One thing the Guelph study does show is that something has changed from an ecological standpoint, saidMassolo, and the fact that the parasite is spreading is increasing the risk to both people and animals.

"In any case, it's a type of infection you don't want."