WATERLOO REGION—Dogs and humans can be infected by a potentially deadly tapeworm that University of Guelph researchers say is now in Southern Ontario.

The tapeworm, Echinococcus multilocularis, wasn’t thought to be present in Ontario until five sick dogs from the west side of Lake Ontario — in the Golden Horseshoe area — were identified between 2012 and 2016.

One of the infected dogs was from Guelph, said Andrew Peregrine, a professor at Guelph’s Ontario Veterinary College and one of the authors of a published study on the tapeworm’s presence in the province.

After the cluster of infections was found, Peregrine and the chief medical officer of health for the Guelph area spoke up.

“She said, ‘You folks have got to map where this parasite is in Ontario because, at the moment, it’s not on the radar of any physicians because we’re not supposed to have it in Ontario,’” he said.

At that point, the tapeworm was known to exist in the southern part of the Prairie provinces and in bordering states but not in Ontario, he said.

“Unlike the tapeworms that typically occur in dogs and cats, this one is really nasty,” Peregrine said, adding that it can cause disease of the liver and, if left untreated, can spread to other organs and cause death in dogs and humans.

From 2015 to 2017, Peregrine and a team of researchers tested 460 foxes and coyote carcasses in southern Ontario the tapeworm. The carcasses were from licensed hunters and trappers and the Ontario Ministry of Natural Resources and Forestry. Of those tested, 23 per cent were infected.

“Now we’ve got clear evidence it’s widespread in southern Ontario,” Peregrine said. “The concern about that is now that it’s a very common infection in foxes and coyotes, it’s very likely it will spill over into dogs.”

And if it spreads to dogs, it can potentially infect their human companions.

Dogs, coyotes and foxes get the tapeworm if they eat an infected rodent. They then carry the adult parasite in their small intestine but don’t get sick.

If the animals eat the tapeworm’s eggs — found in the feces of infected animals — they develop a deadly infection called alveolar echinococcosis or AE. The majority of the five dogs found between 2012 and 2016 with the infection died, he said.

Humans can get this infection by ingesting eggs found in feces, as well. Peregrine said this can happen when you pick up your pet’s waste and don’t wash your hands or even from sleeping in the same bed as a dog who has feces on its coat. Unlike other tapeworms, this one is very tiny, and humans would not be able to see it.

The incubation period of the disease in humans is between five and 15 years. It can cause jaundice, abdominal pain, fatigue and weight loss, and needs to be treated.

“(For) about a third of people (infected), the surgeons can remove all the parasite from the liver — they’ll just cut it out,” Peregrine said. “The rest go into long-term chemotherapy.”

Most dogs who have developed the disease are treated the same way, he added.

Peregrine said not all dogs are at risk of carrying the tapeworm. He recommends pet owners speak with their veterinarians for advice.

“If (your dog) never goes outside or hardly goes outside the backyard, then the risk of this is minimal,” he said. “But if your dog goes off leash and you know it hunts or eats rodents ... then there is a drug you can give the dogs regularly to stop them from developing intestinal infections.”

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Last year, partly because of the Guelph study, Ontario became the first province in the country to make it mandatory for physicians and veterinarians to report all human and animal cases to local public health departments.

Peregrine said there have been a couple of human cases reported.

He and his team are now leading a followup study to determine how prevalent the tapeworm is in dogs. They have collected fecal samples from 10 dog parks across the Golden Horseshoe area and will soon begin testing.