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What
is trichinellosis?
Trichinellosis, also called trichinosis, 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 carnivorous (meat-eating) animals but may also occur in domestic
pigs.
What are the symptoms of a trichinellosis
infection?
Nausea, diarrhea, vomiting, fatigue, fever, and abdominal discomfort
are the first symptoms of trichinellosis. Headaches, fevers, 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
range from very mild to severe and relate to the number of infectious
worms consumed in meat. Often, mild cases of trichinellosis are never
specifically diagnosed and are assumed to be the flu or other common
illnesses.
When a human or animal eats meat that contains infective Trichinella
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 encyst
(become enclosed in a capsule). Infection occurs when these encysted
worms are consumed in meat.
If you eat raw or undercooked meats, particularly bear, pork, wild
feline (such as a cougar), fox, dog, wolf, horse, seal, or walrus, you
are at risk for trichinellosis.
No. Infection can only occur by eating raw or undercooked meat containing
Trichinella worms.
See your health care provider who can order tests and treat symptoms
of trichinellosis infection. If you have eaten raw or undercooked meat,
you should tell your health care provider.
A blood test or muscle biopsy can show if you have trichinellosis.
Several safe and effective prescription drugs are available to treat
trichinellosis. 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.
Infection was once very common and usually caused by ingestion of undercooked
pork. However, infection is now relatively rare. During 1997-2001, an
average of 12 cases per year were reported. The number of cases has
decreased because of legislation prohibiting the feeding of raw-meat
garbage to hogs, commercial and home freezing of pork, and the public
awareness of the danger of eating raw or undercooked pork products.
Cases are less commonly associated with pork products and more often
associated with eating raw or undercooked wild game meats.
- Cook
meat products until the juices run clear or to an internal temperature
of 170 o F.
- Freeze
pork less than 6 inches thick for 20 days at 5 o F 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 with trichinellosis.
- Clean
meat grinders thoroughly if you prepare your own ground meats.
- Curing
(salting), drying, smoking, or microwaving meat does not
consistently kill infective worms.
For more information:
CDC. Trichinellosis surveillance-United States, 1997-2001. In: CDC
Surveillance Summaries (July 25). MMWR 2003; 52 (No. SS-6): 1-8.
Moorhead A, Grunenwald PE, Dietz VJ, Schantz PM. Trichinellosis in the
United States, 1991-1996: Declining but not gone. Am J Trop Med Hyg 1999;
60:66-69.
This fact sheet is for
information only and is not meant to be used for self-diagnosis or as a
substitute for consultation with a health care provider. If you have any
questions about the disease described above or think that you may have a
parasitic infection, consult a health care provider.
 Trichinellosis
 Trichinellosis
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