A fox parasite that can spread to dogs and humans has made another appearance in the Pacific Northwest, researchers at Washington State University said Tuesday.
Commonly known as the fox tapeworm, Echinococcus multilocularis is native to Europe and Asia. It infects foxes and coyotes and can also affect dogs. When it affects humans, researchers said, it can make them ill with a rare but serious disease called alveolar echinococcosis, one of the most deadly parasitic infections known.
The disease can lie dormant in the body for years, silently destroying the liver before symptoms become noticeable, researchers said.
Symptoms can develop five to 15 years after contracting the parasite and include upper abdominal pain, weakness, weight loss and jaundice. Research says the symptoms can often be confused with liver cancer. The World Health Organization estimates it affects more than 18,000 people globally every year.
The parasite grows in the liver similarly to a tumor or cyst and often requires surgical removal once it becomes advanced, researchers said. It is one of the most deadly parasitic infections known to humans, with up to a 90% mortality rate within 10 to 20 years if left untreated, researchers said.
The parasite grows similarly in dogs, but unlike humans, dogs have an 82% survival rate if treated within the first 100 days, according to a study in the National Library of Medicine.
Scientists discovered the worm while dissecting a 9-week-old fox kit found on the WSU campus in Pullman in May. Researchers also found a significant presence of the parasite during studies earlier in the year on coyotes in the Puget Sound area.
“What was surprising was the sheer number of small tapeworms in the intestine,” Kyle Taylor, a veterinarian and pathologist at Washington State University’s Washington Animal Disease Diagnostic Laboratory, said in a news release. “For an animal that young, that kind of burden can take a significant nutritional toll and likely contributed to its decline.”
Since the parasite spreads through feces, officials warn that humans should avoid contact with animal feces and keep their pets from eating wildlife droppings.
While foxes and coyotes are the main mammal carriers, avoiding contact with rodents is equally important, researchers said. Rodents, including mice and squirrels, ingest the parasite’s eggs and pass them to mammals such as foxes through the food cycle.
“There’s likely more of it in the environment than people realize,” Taylor said. “Awareness and basic precautions are the best prevention.”
The U.S. Centers for Disease Control and Prevention warns people to be careful when picking wild berries and other food that may be contaminated by feces. Thoroughly washing food and cooking it can kill the parasite. People should also wash their hands after touching dogs and cats or spending time out in nature, researchers said.
Early detection through blood testing can catch the parasite before it grows, giving patients their best chance at treatment.
