University of Alberta scientists are alerting the public to a potentially lethal tapeworm, which infects humans through the feces of coyotes and dogs.

The rare but "formidable" parasite, Echinococcus multilocularis, has infected four people in Alberta in as many years, researchers said Wednesday.

Researchers have been following the parasite after finding high infection rates in coyotes a few years ago.

"This is significant enough to warrant a watchful eye on the problem," said Stan Houston, a University of Alberta infectious diseases expert.

Houston said the parasite, widely recognized in Europe, is rare in North America, but the potential consequences are life threatening.

If left untreated, the parasite can kill its human host in 10 to 15 years, researchers said.

In most cases, the early presence of Echinococcus multilocularis has no symptoms.

"If the tapeworm goes unnoticed, it can spread to other parts of the body, much like how cancer invades and destroys organs," he added.

The infestation grows slowly, on average 14 cubic centimetres a year. By the time it's found, it may be inoperable.

How parasite is transmitted

People can get the tapeworm from eating foods exposed to traces of canine feces and should be especially vigilant in washing vegetables grown close to the ground.

Houston said we should also be aware of microscopic traces of pet feces in our pets' hair.

"When we pet them and then touch our food or our mouths, we ingest the parasite's eggs," he said.

The parasite is largely harmless to dogs and coyotes — only on rare occasions leading to illness or death.

Researchers recommend pet owners get their pets dewormed on a regular basis if they eat rodents or the feces of other dogs.

Standard dog deworming does not cover the tapeworm, but veterinarians can suggest the proper medication.

Houston said the parasite is an example of the ecological interaction between human and animal health.

"Most emerging infectious diseases come from animals and now here is another one right on our doorstep."