Public inquiries about a wolf-borne tapeworm have prompted the state to publish a fact sheet on the parasite.

The Montana Department of Fish, Wildlife and Parks included the three-page document with its weekly wolf report on Tuesday. The echinococcus granulosus fact sheet discusses the tapeworm’s life cycle, how people and their pets can become infected as well as ways to avoid infection.

“Since there were questions coming in from different areas, we decided to put together the fact sheet,” said Carolyn Sime, wolf project manager for FWP.

The presence of the tapeworm in wolves living in Montana and Idaho was first documented in a study by Montana and Idaho veterinarians and a Washington parasitologist. They published their findings last year in an article in the Journal of Wildlife Diseases, the conclusions of which were widely disseminated by e-mail and the Internet.

“The Internet makes information move a lot faster, and misinformation moves a lot faster, too,” Sime said.

Hamilton veterinarian Cliff Manley thinks the researchers downplayed the dangers of the tapeworm and its possible transmission to humans.

But Robert Rausch, a parasitologist at the University of Washington in Seattle who began researching echinococcus granulosus in 1949, said the documentation of infections in humans has been small and mainly tied to Inuit people who lived with numerous sled dogs.

The tapeworm is transmitted to the dogs when they eat an infected animal’s organs. In Alaska, caribou and moose carried the tapeworm. Once the dogs are infected, they can transmit the eggs of the tapeworm through their feces. In humans, digestion of the eggs can lead to cysts in the lungs and liver, called hydatid disease.

According to FWP’s fact sheet, developed by FWP’s wildlife laboratory supervisor and wildlife veterinarian, “Eggs could be ingested while consuming vegetation or drinking water that has been contaminated with feces. Humans could also become infected by not washing their hands before eating if they’ve handled canine scats or contaminated canine fur.”

The fact sheet goes on to state that in the United States, Utah has had the highest number of surgical human cases — 45 —of a domestic biotype of E. granulosus considered to be more dangerous. This other biotype is more typically found in sheep and dogs, not elk and wolves.

Rausch’s work documented 300 cases of hydatid disease in people in Alaska. Of those, only one person died of what he said was anaphylactic shock. Surgeons with the U.S. Public Health Service were initially removing the cysts, Rausch said, but stopped since the infected people showed no ill effects.

When Rausch first started his work, the number of dogs in a village was twice the number of people, he said. As snowmobiles became more popular and fewer people kept large dog teams, the incidence of E. granulosus infection dropped significantly.

“People were infected by dogs, wolves had nothing to do with it,” he said, except to keep the tapeworm alive for part of its life cycle.

In a study on St. Lawrence Island, Rausch found that 100 percent of the arctic foxes on the island were infected with echinococcus. Although island residents commonly trapped the animals and skinned them, there was no incidence of transmission from the foxes to people.

Whether the tapeworm was transported to the Yellowstone area by infected Canadian wolves transported to the park, despite their inoculation, is unknown but possible, Sime said.

“The probability is never zero,” she said. “Our goal is really to get the facts out. Hunters need to know this stuff is out there.”

Contact Brett French at or at 657-1387.


To prevent E. granulosus infection, FWP advises:
• Do not allow your dog to eat wild or domestic ungulate carcasses.
• If your dog does have access to carcasses, talk to your veterinarian about deworming the dog.
• Always wash your hands after handling a dog that has access to ungulate carcasses.
• Do not touch or disturb wolf, coyote or fox scat.
• Hunters should wear gloves when field dressing a wolf, coyote, or fox carcass and wash their hands and forearms.