Brain parasites infect six in South Dakota

By Claire Wolters | Fact-checked by Davi Sherman
Published June 10, 2024

Key Takeaways

  • A family in South Dakota developed a rare brain parasite after eating undercooked bear meat at a family reunion.

  • Now, the CDC is warning people to thoroughly cook meat in order to avoid these risks.

Six people in South Dakota have been diagnosed with brain parasites following a meaty meal at a family reunion. Now, the Centers for Disease Control and Prevention (CDC) is warning people to thoroughly cook meat products to reduce the risk of infection.[] 

What do we know about the South Dakota infection?

The family in South Dakota was infected with parasites of the genus Trichinella. Trichinella can linger in the striated muscles of wild animals like bears, moose, and wild boar and produce Trichinellosis. Trichinellosis is rare in humans, but cases can occur, as demonstrated. People can be at risk of this infection if they eat undercooked meat from infected animals.[] After ingesting raw or undercooked meat from an infected animal, the parasite can enter the digestive system in larval form.[] The larvae typically grow into adult worms in the small bowel, producing more larvae that migrate to striated muscles.[]

This appears to be what happened to the family members in South Dakota, most of whom ate bear kabobs at their reunion, according to an investigation by the CDC. [] Those who ate the meat said they initially noticed it was undercooked and then threw it back on the grill. Two of the infected family members claimed not to have eaten any bear meat but to have eaten vegetables that had been cooked with it.

What are the risks of Trichinellosis?

Trichinellosis infections can range from mild to severe.[] According to the CDC, light infections can be asymptomatic, while symptoms of more mild infections may vary based on where the parasite has migrated. Some infections can also be life-threatening.

Parasites that invade the intestines may produce symptoms like:

  • Diarrhea

  • Abdominal pain

  • Vomiting

Parasites that migrate into the muscle tissues, a progression that can occur one week after infection, can produce more severe symptoms like:

  • Periorbital and facial edema

  • Conjunctivitis

  • Fever

  • Myalgias

  • Splinter hemorrhages

  • Rashes

  • Peripheral eosinophilia

Parasites that encyst in the muscles can cause symptoms like:

  • Myalgia

  • Weakness

Occasionally, infections can cause life-threatening symptoms; these may happen if the parasite impacts the heart or brain. Some life-threatening symptoms include:

  • Myocarditis

  • Central nervous system involvement 

  • Pneumonitis

  • Brain inflammation (encephalitis)[]

How can doctors diagnose and treat Trichinellosis?

Trichinellosis is rare in humans, so it may not be your go-to diagnosis for most patients. However, don’t exclude it entirely from your list.

Assessing symptoms and asking a patient about their recent eating patterns may help you assess whether they have contracted this parasite. For instance, if a patient mentions eating bear, you may want to be more suspicious. From there, blood tests can also help detect trichinellosis. According to the Cleveland Clinic, if a blood test shows high levels of the white blood cell eosinophils, this can be a warning sign.[]

Treatment for trichinellosis can involve anti-parasite drugs like mebendazole and albendazole and anti-inflammatory drugs like steroids or nonsteroidal anti-inflammatory drugs (NSAIDs).

What this means for you

Trichinellosis is a rare but dangerous parasitic infection that people can contract from eating undercooked meat from wild animals like bear, wild boar, and moose. To avoid this infection, encourage patients to thoroughly cook meat before consumption and to stay away from anything that looks risky or undercooked. 

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