Calgary researchers say a parasite that can prove fatal to humans is expanding its foothold in North America, but not enough is known about how it's being transmitted to effectively stop the spread.

The study, published in Parasite Journal, warns that recent findings suggest the parasite is expanding its range in North America.

Coyotes, foxes, wolves, cats and dogs can pick up the parasite, a tapeworm called echinococcus multiocularis, from rabbits and small rodents. The tapeworm is generally harmless to the canines, but can be deadly for rodents.

"It invades the liver and potentially invades all the other organs in the abdominal cavity and rodents can actually die within five months of infection," University of Calgary researcher Stefano Liccioli told CTV Calgary on Tuesday.

According to the Public Health Agency of Canada, the tapeworm can cause parasitic tumours in the liver, lungs, brain and other organs. If untreated, the parasite can be fatal.

Liccioli said that the tiny parasite is common in animals, but very rare in humans.

Just three cases have been reported in North America -- Manitoba in 1928, Minnesota in 1977 and Alberta in 2013 -- but more than 100 cases have been reported in Europe.

The study, co-written by Liccioli, warns that human parasitic infections may be under-diagnosed in North America.

"We hypothesize that a lack of knowledge about (the parasite) by North American physicians might result in the misdiagnosis of cases and an underestimation of the disease instance," the article says.

In Calgary, the infection rate of coyotes remains steady, at approximately 30 per cent, but in some areas infection rates are far above average.

Alessandro Massolo, co-author and University of Calgary assistant professor of a wildlife disease ecology course, found that as many as 90 per cent of coyotes in Alberta’s Bowmont Park carried the parasite, and rates were also high in the Nose Hill area.

"The endemic presence of the parasite in urban areas and a recent human case in Alberta, Canada suggests the scientific community may need to reconsider the local public health risks, re-assess past cases that might have been overlooked and increase surveillance efforts to identify new cases," the research says.

Calgary dog owners are reminded to deworm their dogs regularly and pick up after their pets to help stem the spread.

Anyone who visits the parks should wash their hands after spending time outdoors and avoid eating low-lying berries.

With a report from CTV Calgary's Bill Macfarlane