What is trichinosis?
Trichinosis (also called Trichinellosis) is caused by eating raw or undercooked meat of animals infected with the larvae of a species of worm called Trichinella. Infection occurs commonly in certain wild meat-eating animals, but may also occur in domestic pigs.
What are the symptoms?
Nausea, diarrhea, vomiting, fatigue, fever, and abdominal discomfort are the first symptoms.Headache, fever, chills, cough, eye swelling, aching joints and muscle pains, itchy skin, diarrhea, or constipation follow the first symptoms. If the infection is heavy, patients may experience difficulty coordinating movements, and have heart and breathing problems. In severe cases, death can occur. For mild to moderate infections, most symptoms subside within a few months. Fatigue, weakness and diarrhea may last for months.
How soon after infection will symptoms appear?
Abdominal symptoms can occur 1-2 days after infection. Further symptoms usually start 2-8 weeks after eating contaminated meat. Symptoms may be very mild or severe. This depends on the number of infectious worms consumed in meat. Mild cases are often never specifically diagnosed and are assumed to be the flu or other common illnesses.
How does infection occur in humans and animals?
When a human or animal eats meat that contains infective cysts, the acid in the stomach dissolves the hard covering of the cyst and releases the worms. The worms pass into the small intestine and, in 1-2 days, become mature. After mating, adult females lay eggs. Eggs develop into immature worms, travel through the arteries, and are transported to muscles. Within the muscles, the worms curl into a ball and become enclosed in a capsule (cyst). Infection occurs when these worms are consumed in meat.
Am I at risk?
You are at risk if you eat raw or undercooked meats, particularly bear, pork, wild feline (such as a cougar), fox, dog, wolf, horse, seal or walrus.
Can I spread it to others?
No. Infection can only occur by eating raw or undercooked meat containing these worms.
What should I do if I think I have it?
See your health care provider who can order tests and treat the symptoms. If you have eaten raw or undercooked meat, you should tell your health care provider.
How is it diagnosed?
A blood test or muscle biopsy can show if you are infected.
How is it treated?
Several safe and effective drugs are available to treat this. Treatment should begin as soon as possible and the decision to treat is based upon symptoms, exposure to raw or undercooked meat, and laboratory test results.
How can I prevent infection?
- Cook meat products to an internal temperature of 74°C.
- Freeze pork less than 6 inches thick for 20 days at -18°C to kill any worms.
- Cook wild game meat thoroughly. Freezing wild game meats, unlike freezing pork products, even for long periods of time, may not effectively kill all worms.
- Cook all meat fed to pigs or other wild animals.
- Do not allow hogs to eat uncooked carcasses of other animals, including rats, which may be infected.
- Clean meat grinders thoroughly if you prepare your own ground meats.
- Curing (salting), drying, smoking, or microwaving meat does not consistently kill infective worms.
Centers for Disease Control & Prevention, Trichinellosis, March 2008.