Trichinosis, 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
. Infection occurs worldwide, but is most common
in areas where raw or undercooked pork, such as ham or sausage, is
What are the symptoms of a trichinosis infection?
Nausea, 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. 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
trichinosis are 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
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
Am I at risk for trichinosis?
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 trichinosis.
Can I spread trichinosis to others?
No. Infection can only occur by eating raw or undercooked meat
How is trichinosis infection diagnosed?
See your 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. A
blood test or muscle biopsy can show if you have trichinosis.
How is trichinosis infection treated?
Several 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 test results.
Is trichinosis common in the United States?
Infection 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 trichinosis?
Cook meat products until the juices run clear or to an internal
temperature of 170 o F.
Freeze pork less than six 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 trichinosis.
Clean meat grinders thoroughly if you prepare your own ground
Curing (salting), drying, smoking, or microwaving meat does not
consistently kill infective worms.
Centers for Disease Control and
Prevention, August 1999
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a