Man’s best friends may be spreading a potentially deadly parasite originally from Europe.
Research led by the University of Calgary’s faculty of veterinary medicine has found that a strain of tiny tapeworm that can make people seriously ill has become common in Alberta wildlife.
“It’s not your classic tapeworm that you think of … not the long tapeworms that live in your intestines. They are very small. You can hardly see them with your bare eye,” said Dr. Claudia Klein, a veterinarian and associate professor at the university.
Researchers say six people in the province have been diagnosed with the potentially fatal parasite since 2016. There have also been cases reported in Quebec.
Recent studies have found a high incidence of infected coyotes, foxes, and rodents across Alberta, including in urban off-leash dog parks in Calgary.
The tapeworm is spread through the feces of coyotes and foxes that have eaten infected rodents. Dogs can get the parasite in turn through contact with the feces or by eating infected rodents.
The worm can be passed on to people on fruit or vegetables, by handling contaminated soil or through an infected pet’s fur.
The condition, known as human alveolar echinococcosis, or AE, develops slowly over several years and causes multiplying lesions in the body.
“One of the problems is you don’t become sick immediately. Once you’re exposed, then maybe you get sick eight to 10 years down the road as a human. And you would then have the same tumourlike lesions in your liver,” said Klein.
It can be fatal if not diagnosed in time, especially in people who have a compromised immune system. Hunters and trappers could be at a higher risk of being infected, Klein said.
The parasite can be diagnosed with a simple blood test.
It can be killed in pets with a dewormer specifically for tapeworms, Klein said.
The research from Klein, Dr. Alessandro Massolo (now at the University of Pisa in Italy) and Dr. Kinga Kowalewska-Grochowska of the University of Alberta, was shared in a letter to the editor in the latest issue of the New England Journal of Medicine.
“This evidence is the smoking gun that these AE cases are locally acquired, and they are caused by an invasive strain coming from Europe that has spread all over Alberta,” said Massolo.
“This European strain is known to be very virulent for people, and now is everywhere in wildlife and even in dogs.”
Klein said a number of infected canines could have been brought in as pets from Europe over the last 10 or 20 years, and foxes were being brought in for hunting purposes in eastern Canada.
The parasite is particularly problematic in China, which records up to 110,000 human cases a year. In Europe, the number is about 110.
Klein said some cases in Canada may have gone undiagnosed in the past.
“This disease was never on the radar of doctors because they have considered it sort of like a foreign disease.,” she said.
“You may have heard about it in medical school and then if you never see a disease you don’t think about it.”
Our Morning Update and Evening Update newsletters are written by Globe editors, giving you a concise summary of the day’s most important headlines. Sign up today.