What is trichinosis?

Trichinosis, sometimes called trichinellosis, is a type of roundworm infection. Roundworm parasites use a host body to live and reproduce. Occurring primarily among meat-eating animals (carnivores) — especially bears, foxes and walruses — the infection is acquired by eating roundworm larvae in raw or undercooked meat.

When humans eat undercooked meat containing trichinella larvae, the larvae mature into adult worms in the intestine over several weeks. The adult worms then produce larvae that travel through various tissues, including muscle. Trichinosis is most widespread in rural areas throughout the world.

Trichinosis can be treated with medication, though it’s not always necessary. It’s also easy to prevent.

How common is trichinosis?

Please discuss with your doctor for further information.


What are the symptoms of trichinosis?

Trichinosis symptoms vary, depending on the stage of infection, number of invading larvae, tissues invaded, and general physical condition of the person. Many people have no symptoms.

Symptoms of trichinosis occur in two stages.

  • Stage 1: Intestinal infection develops 1 to 2 days after eating contaminated meat. Symptoms include nausea, diarrhea, abdominal cramps, and a slight fever.
  • Stage 2: Symptoms from the larval invasion of muscles usually start after about 7 to 15 days. Symptoms include muscle pain and tenderness, weakness, fever, headache, and swelling of the face, particularly around the eyes. The pain is often most pronounced in the muscles used to breathe, speak, chew, and swallow. A rash that does not itch may develop. In some people, the whites of the eyes become red, and their eyes hurt and become sensitive to bright light.

If many larvae are present, the heart, brain, and lungs may become inflamed. Heart failure, abnormal heart rhythms, seizures, and severe breathing problems may result. Death can occur but is rare.

Without treatment, most trichinosis symptoms disappear by the third month of infection, although vague muscle pain and fatigue can persist longer.

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.


What causes trichinosis?

People get trichinosis when they eat undercooked meat — such as pork, bear, walrus or horse — that is infected with the immature form (larvae) of the trichinella roundworm. In nature, animals are infected when they feed on other infected animals. Pigs and horses can become infected with trichinosis when they feed on garbage containing infected meat scraps. Cattle don’t eat meat, but some cases have been linked to eating beef that was mixed with infected pork or ground in a grinder previously used for contaminated pork.

Risk factors

What increases my risk for trichinosis?

There are many risk factors for trichinosis, such as:

  • Improper food preparation. Trichinosis infects humans when they eat undercooked infected meat, such as pork, bear or walrus, or other meat contaminated by grinders or other equipment.
  • Rural areas. Trichinosis is more common in rural areas. In the United States, higher rates of infection are found in hog-raising regions.
  • Consumption of wild or noncommercial meats. Public health measures have greatly decreased the incidence of trichinosis in commercial meats, but noncommercial, farm-raised animals have higher rates of infection — particularly those with access to wild-animal carcasses. Wild animals, such as bears and walruses, are still a common source of infection.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is trichinosis diagnosed?

Unlike most other worm infections, trichinosis cannot be diagnosed by microscopic examination of the stool. Blood tests for antibodies to Trichinella spiralis are fairly reliable, but they are not positive until 3 to 5 weeks after symptoms start. If the results are negative, a doctor usually bases an initial diagnosis of trichinosis on symptoms and the presence of elevated levels of eosinophils (a type of white blood cell) in a blood sample. The antibody test is repeated several weeks later to confirm the diagnosis.

A biopsy of muscle tissue (in which a sample of tissue is removed and examined under a microscope), done after the second week of infection, may reveal larvae or cysts but is seldom necessary.

How is trichinosis treated?

Trichinosis usually isn’t serious and often gets better on its own, usually within a few months. However, fatigue, mild pain, weakness and diarrhea may linger for months or years. Symptomatic infections may respond to treatment with medication.

  • Anti-parasitic medication. Anti-parasitic (anti-helminthic) medication is the first line of treatment against trichinosis. If the trichinella parasite is discovered early, in the intestinal phase, albendazole (Albenza) or mebendazole can be effective in eliminating the intestinal worms and larvae. You may have mild gastrointestinal side effects during the course of treatment. If the disease is discovered after the larvae bury themselves in tissues, the benefit of anti-parasitic medications is less certain. Your doctor might prescribe one if you have central nervous system, cardiac or respiratory problems as a result of the invasion.
  • Pain relievers. After muscle invasion, pain relievers may be given for muscle aches. Eventually, the larvae cysts in your muscles tend to calcify, resulting in destruction of the larvae and the end of muscle aches and fatigue.
  • Some cases of trichinosis cause allergic reactions when the parasite enters muscle tissue or when dead or dying larvae release chemicals in your muscle tissue. Your doctor might prescribe a corticosteroid to control inflammation during larval migration.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage trichinosis?

The following lifestyles and home remedies might help you avoid trichinosis:

  • Avoid undercooked meat. Be sure whole cuts of meat other than poultry and wild game are cooked to an internal temperature of 145 F (63 C) throughout, and don’t cut or eat the meat for at least three minutes after you’ve removed it from the heat. Cook ground pork and beef to at least 160 F (71 C). They can be eaten immediately after cooking. Using a meat thermometer is the best way to ensure the meat is thoroughly cooked.
  • Avoid undercooked wild game. For both whole cuts and ground varieties, cook to an internal temperature of at least 160 F (71 C).
  • Avoid undercooked poultry. For whole cuts and ground varieties, cook to a temperature of at least 165 F (74 C). For whole cuts, let the poultry sit for three minutes before cutting or eating.
  • Have wild-animal meat frozen or irradiated. Irradiation will kill parasites in wild-animal meat, and deep-freezing for three weeks kills trichinella in some meats. However, trichinella in bear meat does not die by freezing, even over a long period. Neither irradiation nor freezing is necessary if you ensure that the meat is thoroughly cooked.
  • Know that other processing methods don’t kill parasites. Other methods of meat processing or preserving, such as smoking and pickling, don’t kill trichinella parasites in infected meat.
  • Clean meat grinders thoroughly. If you grind your own meat, make sure the grinder is cleaned after each use.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: January 4, 2018 | Last Modified: January 4, 2018

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