A dangerous tapeworm called Echinococcus multilocularis has been found for the first time in wild animals along the West Coast of the United States. Researchers from the University of Washington tested 100 coyotes near Puget Sound and learned that 37 of them carried the parasite.
How the Tapeworm Lives
The adult worms live in the intestines of coyotes, foxes and other wild dogs. These animals usually feel fine, but they drop thousands of tiny eggs in their poop.
Small rodents eat the contaminated food, become sick, and develop tiny cysts in their livers. When a coyote catches and eats an infected rodent, the cycle starts again.
People and pet dogs can get infected by accident. Swallowing an egg – for example from food that touched coyote or dog feces – can lead to a disease called alveolar echinococcosis. The disease creates slow‑growing, cancer‑like cysts in the liver and can be deadly if not treated.
Risk to Pets and People
Most dogs that pick up the parasite do not become sick right away. However, if they eat the eggs, they can develop the same dangerous liver cysts that affect humans.
Regular veterinary check‑ups, stool tests and preventive deworming medicines are the best ways to keep dogs safe.
Why This Finds Matter
Earlier reports of the tapeworm in North America involved a less aggressive “tundra” strain. The new cases involve a more contagious European strain that spreads easily among coyotes.
Even though more than a third of the studied coyotes carried the parasite, only a handful of dog cases and no human cases have been recorded on the West Coast so far.
What Can Be Done
Keep dogs away from raw wild rodents, wash hands after outdoor activities, and avoid letting pets eat dead animals. These simple steps greatly lower the chance of infection.