Tapeworm could jump to humans, vet warns

SASKATOON A Saskatoon veterinarian says “there’s a very good chance” Saskatchewan could see human cases of a potentially lethal tapeworm in the foreseeable future.

Echinococcus multilocularis is a tapeworm less than four millimetres long. Its life cycle begins when small rodents, such as mice and voles, eat its eggs, which then form cysts on their liver, lungs, brain and other organs. When dogs or cats eat infected rodents, larvae within the cysts develop into adult tapeworms. Dogs and cats release tapeworm eggs in their excrement, which can be eaten by rodents to restart the tapeworm’s life cycle.

Humans can inadvertently consume tapeworm eggs if they handle the excrement of infected dogs and then touch their own food, or if they eat things — such as berries, mushrooms or herbs — that are contaminated by infected dog or cat droppings.

If that happens, tapeworm cysts can spread to the person’s liver and other organs like a tumour.

Emily Jenkins, a professor of veterinary parasitology and public health at the University of Saskatchewan, said unless the disease is identified and treated quickly, the mortality rate is between 50 per cent and 75 per cent. Treatment involves surgery to remove the cysts and years of drug therapy.

“When you do get it, it’s really serious,” Jenkins said.

“We need people to have this on their radar. When they look at something that looks like a liver tumour, in the back of their minds they need to think, ‘Or it could be this weirdo tapeworm,’ because the drugs that you would use to manage a liver cancer are not the ones you need to be using for the tapeworm.”

“We know the parasite’s here; there’s a very good chance we’re going to start seeing human cases in Saskatchewan,” Jenkins said.

E. multilocularis is more common in Asia and Europe than in North America, but she said research she has done since 2009 suggests that about one-quarter of coyotes, foxes and wolves in North America are infected by the tapeworm.

Jenkins said it’s hard to know how quickly the parasite is spreading. There’s no formal surveillance in place for the tapeworm and symptoms in humans can take more than five years to develop. Jenkins said the risk for human infection increases if their fourlegged companions go to dog parks. She recommends dog owners wash their hands thoroughly after scooping poop, keep dogs onleash and away from wild dog and rodent droppings, and deworm high-risk pets every month.