EDMONTON -- Doctors at the University of Alberta are raising the alarm about a rare tapeworm that, until recently, hadn't been seen in humans in Canada since the 1920s.
The worm is harmless to coyotes and other dogs, but can spread like a slow-moving cancer in humans and is potentially deadly if untreated.
Infectious disease expert Stan Houston says there have been four cases in Alberta in the last four years and the only other one in Canada was in Manitoba in 1928.
He says that's a rate that is worth keeping an eye on.
The researchers say dogs get the tapeworm from eating infected rodents and it can be spread to humans by eating vegetables that came in contact with dog feces or through microscopic traces of feces on the hair of a dog that hunts rodents.
Its spread can be prevented by having dogs dewormed on a regular basis and by thoroughly washing vegetables that grow close to the ground.
Early infestation in humans is without symptoms, but because the worm, Echinococcus multilocularis, travels to the liver, some patients will turn yellow or report unspecified pain.
In humans, the parasite can be removed surgically and, even if it has spread to the point where surgery is not an option, patients can still live with it by taking anti-parasitic medication.
"The public should not be overly worried about getting this disease as it is rare in North America," said Dr. Klaus Buttenschoen in a news release Wednesday. "People with low immunity are at greater risk."
Houston said the worm is likely to have been brought to Canada through an infected dog from Europe.
"This is an important example of the inescapable ecological interaction between human and animal health," he said. "Most emerging infectious diseases come from animals and now here is another one right on our doorstep."
