A family gathering ended up with six people getting trichinellosis — colloquially known as “brain worms” — after eating undercooked bear meat, the U.S. Center for Disease Control reports.

Relatives from Arizona, Minnesota, and South Dakota gathered in South Dakota for several days, the report said, and one family member had brought along bear meat. It had been previously frozen “to kill parasites.” 

The meat was “thawed and grilled with vegetables” in the form of kabobs, the report noted, adding that it was “initially inadvertently served rare, reportedly because the meat was dark in color, and it was difficult for the family members to visually ascertain the level of doneness.”

Once family members noticed the meat wasn’t fully cooked, it was “recooked before being served again.”

As the National Library of Medicine explains, trichinellosis is a “parasitic infection caused by roundworms…larvae enter the lymphatic circulation and then into the blood, reaching skeletal muscles, myocardium, and brain which are high in oxygen content.”

A week after the meal, a 29-year-old man who ate the meat became ill, and was hospitalized twice in a 17-day period. His symptoms included fever, severe myalgias (muscle aches and pains), periorbital edema (swelling around the eyes) and “other laboratory abnormalities,” the CDC report says. It was during his second hospitalization when he shared that he’d eaten bear meet, prompting health authorities to suspect trichinellosis and notify the Minnesota Department of Health.

A positive Trichinella immunoglobulin (Ig) G antibody test result confirmed their suspicions — and a test of the bear meat showed the presence of Trichinella larvae. 

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Six family members — ranging in age from 12 to 62 — ended up ill from the meal, even though two of the sickened people “consumed only the vegetables (but no meat).”

Two more family members were hospitalized, but “all six symptomatic persons recovered,” the CDC notes.

Although the National Library of Medicine says pork is usually the source of a trichinellosis infection, the CDC notes in its report that “bear meat was the suspected or confirmed source of infection in the majority of those outbreaks” that have occurred in the US since 2016. 

Treatment of a trichinellosis infection requires “prompt treatment” with antiparasitic medication, the CDC says, “by killing the adult worms and so preventing further release of larvae.”

But the best defense against it is proper food preparation, the Mayo Clinic says.

“Cook pork and meat from wild animals to an internal temperature of 160 F (71 C) at the center,” the Mayo Clinic says. “Use a meat thermometer to make sure the meat is thoroughly cooked.”