Trichinosis

What is trichinosis?

Trichinosis is an infection of the intestine caused by eating food infected by the parasite Trichinella spiralis.

Trichinosis is rare in the US. However, it is more common among Southeast Asian immigrants because of some ways they use to prepare food.

This infection is also called trichinellosis.

How does it occur?

You can get trichinosis by eating raw or inadequately cooked pork or wild game products. The parasite is a roundworm whose eggs (cysts) can be in raw meat or meat that hasn't been cooked enough. New worms emerge from these eggs in the stomach or intestine and reproduce in your intestines, causing trichinosis. The incubation period (the time between when you eat food containing the eggs and the appearance of the first symptoms of the disease) is generally between 7 and 14 days. However, you might have symptoms as early as a day after you eat contaminated food.

What are the symptoms?

Trichinosis sometimes has no symptoms. When symptoms do occur, they come in three stages: the intestinal stage, the muscular stage, and the convalescent stage.

Symptoms of the intestinal stage occur during the first week. They include:

• abdominal cramps
• generally not feeling well
• occasional nausea, vomiting, or diarrhea
• fever (rare).

Symptoms of the muscular stage, which occur during the first month after infection, are:

• fever
• muscle pain and tenderness
• swelling around the eyes
• sweating
• redness of the part of the eyes that is usually white
• weakness (often severe)
• feeling out of breath
• coughing
• rashes.

During the convalescent stage more severe symptoms may appear, involving other parts of the body by the second month. Symptoms may include:

• muscle pains and a general feeling of poor health that last for several more months
• permanent muscle paralysis
• neurologic, circulatory, and metabolic problems.

How is it diagnosed?

Your health care provider will ask about your symptoms, examine you, and may order tests, such as:

• blood test
• muscle biopsy to look for the larvae or cysts of the parasite.

If you have a muscle biopsy, first you will receive a local anesthetic to numb the skin over the muscle of your upper arm or calf. Your health care provider will make a small cut in the skin and remove a tiny piece of muscle. Your provider will then sew the skin back together. The muscle will be looked at under a microscope for signs of trichinosis.

How is it treated?

Most people who have a mild infection get better without treatment.

For more severe symptoms, your health care provider may prescribe mebendazole or prednisone. Take all your medicine as prescribed. If you quit taking your medicine before you have taken all of it, the infection may come back.

If you have a severe infection, you may need to stay at the hospital. Your health care provider may prescribe high doses of corticosteroids. This medicine helps to control the symptoms. After 24 to 48 hours of high doses, you may then need lower doses for several days or weeks at home.

How long will the effects last?

Mild cases of the infection may last 3 to 5 days. In severe cases the infection may last 1 to 2 months. You may have muscle pains and feel ill for several more months.

How can I take care of myself?

• If you have diarrhea, you may want to let your bowel rest for a few hours by drinking only clear liquids such as water, weak tea, bouillon, apple juice, or sports drinks or oral rehydrating solutions. You may also drink soft drinks without caffeine (such as 7 UP) after letting them lose some of their carbonation (go flat). Make sure you drink often so you do not become dehydrated. Becoming dehydrated can be very dangerous, especially for children, older adults, and some people who have other medical problems. Suck on ice chips or Popsicles if you feel too nauseated to drink fluids.
• It is OK to keep eating as long as it does not seem to worsen diarrhea or stomach cramps. Foods that are easiest to digest are soft starchy foods, such as bananas, cooked cereal, rice, plain noodles, eggs, gelatin, toast or bread with jelly, and applesauce. Avoid milk products and caffeine for a few days. Return to your normal diet after 2 or 3 days, but for several days avoid fresh fruit (other than bananas), alcohol, greasy or fatty foods such as cheeseburgers or bacon, and highly seasoned or spicy foods. Avoid most fresh vegetables. Cooked carrots, potatoes, and squash are fine. If eating seems to worsen diarrhea, let your bowel rest for a few hours by drinking just clear liquids.
• If you have cramps or abdominal pain, it may help to put a hot water bottle or a heating pad (set on low) on your abdomen.
• Make sure you take the medicine your health care provider prescribes.

What can be done to help prevent trichinosis?

• Always cook meat, especially pork and pork products, to the recommended temperature of 170°F (77°C) or higher.
• Freeze pork at 5°F (-15°C) for 20 days to kill the parasite.
• Cook wild game meat thoroughly. Freezing wild game meats, even for long periods of time, may not kill all worms.