Description

Trichinellosis is a disease caused by a parasite (Trichinella sp. roundworm) that lodges itself in the muscles of some animals. It can cause food poisoning in humans who have consumed their meat undercooked.

Animals at risk

Trichinellosis affects a large number of animal species, but is more common in carnivorous or omnivorous animals. In Québec, the black bear is the animal most likely to transmit the disease to humans.

Signs of the disease in animals

Infection is symptom-free in most animals. Parasites cannot be detected by the naked eye in an infected carcass. Larvae in meat can only be detected by laboratory analysis.

Transmission

Infectious larvae are transmitted from animal to animal as a result of eating raw or undercooked infected meat. After ingestion, the worm is released through digestion and reproduces in the intestine. The young larvae then migrate to the different muscles of the animal to lodge themselves and form cysts. The parasite can survive for several months or even years in the muscles.

The parasite responsible for trichinellosis, which was previously associated with the ingestion of undercooked pork, was almost eliminated from this type of livestock. Eating undercooked black bear meat is often the source of infections in humans.

Treatment

Treatment is generally not possible in animals. Management of this disease requires prevention by stopping animals and humans from ingesting meat contaminated with viable Trichinella cysts.

Protection and prevention

It is important to always cook game meat properly, especially species at higher risk of being contaminated with Trichinella (e.g., bear). It is also required to always adopt best practices for handling, preserving and cooking game meat, as well as safety standards for cutting the meat. For more information, you may refer to this document on wild game meat (in French only).

In humans

The severity of the disease depends on the amount of ingested parasites. Within one week of ingesting infected meat, trichinellosis may develop into diarrhea and abdominal discomfort.

One to three weeks after these symptoms, signs of allergy may appear, such as redness on the skin and swelling in the face, particularly the eyelids.

These symptoms may be accompanied by signs of muscle infection, such as:

  • fever;
  • headaches;
  • muscle pain and weakness.

In some cases, muscle pain and weakness may persist for several weeks. In rare cases, complications such as pneumonia and heart or nervous problems can occur.

When to consult and treat

If you have consumed black bear meat and have symptoms, contact Info-Santé 811 as soon as possible. Treatment will be required to remove the worms.

Last update: March 7, 2022

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