Trichinosis Food Poisoning

What is trichinosis?

Trichinosis is a type of food poisoning. It is generally rare in the US but is more common among Southeast Asian immigrants because of some of the ways they prepare food.

This infection is also called trichinellosis.

What is the cause?

The infection is caused by eating food that is infected by the parasite Trichinella spiralis. You can get trichinosis by eating raw or undercooked pork; pork products; or wild, meat-eating game, such as undercooked bear.

The parasite is a roundworm whose eggs (cysts) can be in raw or undercooked meat. New worms hatch from these eggs in your stomach or intestine and reproduce to make more worms in your intestines. The time between when you eat food containing the eggs and when you first start having symptoms of the disease is generally 7 to 14 days. However, it’s possible to start having symptoms as soon as a day after you eat contaminated food.

What are the symptoms?

Trichinosis sometimes does not cause any symptoms. When symptoms do occur, they come in 3 stages: the intestinal stage, the muscular stage, and the convalescent stage.

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

• stomach 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, include:

• fever
• muscle pain and tenderness
• swelling around the eyes
• sweating
• redness of the eyes
• 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
• trouble using some muscles (weakness)

How is it diagnosed?

Your healthcare provider will ask about your symptoms and examine you. You may have tests, such as:

• blood tests to look for signs of infection or other causes of fever and weakness
• muscle biopsy to look for the larvae or cysts of the parasite

If you have a muscle biopsy, you will be given an anesthetic to numb the skin over the muscle of your upper arm or calf. Then your healthcare 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 piece of 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 illness, your healthcare provider may prescribe mebendazole. Take all of 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 healthcare provider may prescribe high doses of corticosteroids, such as prednisone, to help control the symptoms. After 24 to 48 hours of high doses, you may then need lower doses for several days or weeks at home. Using a steroid for a long time can have serious side effects. Take steroid medicine exactly as your healthcare provider prescribes. Don’t take more or less of it than prescribed by your provider and don’t take it longer than prescribed. Don’t stop taking a steroid without your provider's approval. You may have to lower your dosage slowly before stopping it.

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?

• Make sure you take the medicine your healthcare provider prescribes.
• If you have diarrhea, you may want to let your bowel rest for a few hours by not eating any food. Large amounts of watery diarrhea can cause dehydration, so it’s important to replace the fluids you are losing. Do this by drinking clear liquids, such as water, weak tea, bouillon, apple juice, or sports drinks or other oral rehydrating solutions. You may also drink soft drinks without caffeine (such as 7 UP). Let sodas lose some of their carbonation (go flat) before you drink them. Make sure you drink small amounts often. Not getting enough fluids to replace the fluids your body is losing while you are sick can be very dangerous. This is especially true 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’s OK to keep eating as long as it does not seem to make diarrhea or stomach cramps get worse. Foods that are easiest to digest are soft, plain foods, such as bananas, cooked cereal, rice, plain noodles, soft-boiled eggs, gelatin, toast or bread with jelly, and applesauce. Go back to your normal diet after 2 or 3 days, but avoid milk products and caffeine for a few days. For several days also avoid fresh fruit (other than bananas), alcohol, greasy or fatty foods, highly seasoned or spicy foods, and most fresh vegetables. Cooked carrots, potatoes, and squash are OK. If eating seems to make the diarrhea worse, go back to just clear liquids for a few hours. Then again try small amounts of the foods that are easy to digest.
• If you have cramps or stomach pain, it may help to put a hot water bottle or electric heating pad on your stomach. Cover the hot water bottle with a towel or set the heating pad on low so you don’t burn your skin.

How can I 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 (minus 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.