also called trichinellosis (TRICK-a-NELL-o-sis), is caused by eating raw
or undercooked pork and wild game products infected with the larvae of a
species of worm called Trichinella. Infection occurs worldwide, but
is most common in areas where raw or undercooked pork, such as ham or
sausage, is eaten.
What are the
symptoms of a trichinosis infection?
diarrhea, vomiting, fatigue, fever, and abdominal discomfort are the first
symptoms of trichinosis. 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.
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?
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 trichinosis are never specifically diagnosed
and are assumed to be the flu or other common illnesses.
How does infection
occur in humans and animals?
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.
Am I at risk for
If you eat
raw or undercooked meats, particularly pork, bear, wild feline (such as a
cougar), fox, dog, wolf, horse, seal, or walrus, you are at risk for
Can I spread
trichinosis to others?
Infection can only occur by eating raw or undercooked meat containing Trichinella
What should I do
if I think I have trichinosis?
health care provider who can order tests and treat symptoms of trichinosis
infection. If you have eaten raw or undercooked meat, you should tell your
health care provider.
How is trichinosis
test or muscle biopsy can show if you have trichinosis.
How is trichinosis
safe and effective prescription drugs are available to treat trichinosis.
Treatment should begin as soon as possible and the decision to treat is
based upon symptoms, exposure to raw or undercooked meat, and laboratory
common in the United States?
was once very common; however, infection is now relatively rare. From
1991-1996, an annual average of 38 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.
How can I prevent
meat products until the juices run clear or to an internal temperature
of 170 o F.
pork less than 6 inches thick for 20 days at 5 o F to kill
wild game meat thoroughly. Freezing wild game meats, unlike freezing
pork products, even for long periods of time, may not effectively kill
all meat fed to pigs or other wild animals.
allow hogs to eat uncooked carcasses of other animals, including rats,
which may be infected with trichinosis.
meat grinders thoroughly if you prepare your own ground meats.
(salting), drying, smoking, or microwaving meat does not consistently kill
for Disease Control. Trichinosis Surveillance, United States,
1987-1990, MMWR 1991;40:(SS-3)35-42.
A, Grunenwald PE, Dietz VJ, Schantz PM. Trichinellosis in the United
States, 1991-1996: Declining but not gone. Am J Trop Med Hyg 1999;
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.