Family members in U.S. infected with muscle worms after eating undercooked Sask. bear meat

Many people who shared a meal of bear meat, harvested from northern Saskatchewan, at a family gathering in South Dakota were infected with trichinellosis, according to a new report from the U.S. Centers for Disease Control and Prevention.

Experts say the parasite that causes the disease is common in wild meat.

In July 2022, the Minnesota Department of Health was notified that a man, 29, had been hospitalized multiple times over a two-and-a-half-week period with symptoms including fever, severe muscle soreness and swelling around the eyes.

Following his second hospitalization, the man revealed to doctors that he and "eight extended family members from three states" (Arizona, Minnesota and South Dakota) had attended a family gathering where they shared kabobs of black bear meat that "had been harvested by one of the family members in northern Saskatchewan."

Trichinellosis is a parasitic zoonotic disease transmitted through the consumption of meat from animals infected with trichinella nematodes.

"It's unfortunate but unsurprising. Trichinellosis outbreaks in people from eating undercooked bear meat, wild boar, even other animals in southern Canada like walrus, are very common ways that people can contract this parasite," said Douglas Clark, an associate professor in the school of environment and sustainability at the University of Saskatchewan.

Clark said things became difficult for the family because the meat was inadvertently served rare.

After some of the family members began eating the meat and noticed it was undercooked, the report says, the meat was recooked before being served again. 

"Bear meat is often dark purple in color, so if you're not used to cooking bear meat, it can be hard to judge when it's done or not done," Clark said.

The report says the meat had been kept in a household freezer for 45 days until being thawed and grilled with vegetables. 

While some parasites are killed by freezing, Clark says, many common species of trichinella found in Canada can survive it.

"They can only be killed by cooking the meat to a high temperature," he said, noting an internal temperature of at least 74°C is necessary to kill the parasites.

However, members who did not consume the meat and only the vegetables that had been cooked with the meat also had symptoms consistent with trichinellosis.

Clark says that's because trichinella-infected meat can cross-contaminate other foods with contact.