Written by Shannon Johnson | Published on August 20, 2012
Medically Reviewed by George Krucik, MD


What Is Trichinosis?

Trichinosis is a disease caused by a roundworm that is found in animals that eat meat. Humans can be infected when they eat undercooked pig, horse, bear, fox, and walrus meat. The roundworm begins its life cycle in the intestines and then lodges itself in the muscles, causing pain and discomfort.

The Centers for Disease Control and Prevention estimate that 10,000 cases of trichinosis are diagnosed every year worldwide (CDC). With strict laws for meat processing and animal feed, the United States currently has very few reported cases of trichinosis, an average of only 40 per year.

How Do You Contract Trichinosis?

Trichinosis is caused by the larvae of the Trichinella ringworm. The parasitic worm is often found in animals that eat meat. One of the most common carriers of the parasite are pigs. The process by which a human becomes infected is as follows:

  • A person eats contaminated meat that was undercooked and that contains the parasite larvae.
  • Trichinella parasites, when they are living in muscle tissue, surround themselves in a protective capsule called a cyst. Once they are ingested, your stomach juices dissolve the cyst and release the larvae.
  • The larvae enter the intestine where they mature into adult worms and reproduce.
  • Female worms release larvae into the bloodstream, where they migrate via blood vessels and move into the muscles.
  • The larvae then encapsulate into the muscle fibers where they can live for an extended period of time.

Symptoms of Trichinosis

When you are first infected, you may or may not have any symptoms. However, within a week of infection the larvae will enter your muscle tissue. This stage is when symptoms are most noticeable.

After treatment, most of the symptoms will go away within a few months. However, mild pain and fatigue could last much longer. The severity of a person’s infection depends on how much infected meat they ate.

Possible symptoms while larvae are in the intestines:

  • diarrhea
  • abdominal cramps
  • fatigue
  • nausea
  • vomiting

Symptoms after larvae enter your muscle tissue:

  • muscle aches and pains
  • high fever
  • swelling in eyes and face
  • sensitivity to light
  • eye infections
  • rashes
  • headaches
  • cough
  • chills

How Do Doctors Diagnose Trichinosis?

After getting background information from you regarding your symptoms, a doctor might perform a blood test or a muscle biopsy to see if any larvae are present in your system.

A severe infection with trichinosis could cause the following complications, which will appear during diagnostic tests:

  • myocarditis (heart inflammation)
  • encephalitis (brain inflammation)
  • meningitis (inflammation of membranes around your brain and spinal cord)
  • bronchopneumonia (inflammation of your lungs and bronchial tubes)
  • nephritis (kidney inflammation)
  • sinusitis (inflammation of sinus mucous membranes)
  • pneumonia (lung inflammation)

Treating Trichinosis

Unfortunately, the worm infection in muscle that accompanies trichinosis cannot be cured. Doctors will focus on treating your symptoms. The earlier your treatment begins, the better your prognosis. Doctors will usually prescribe a combination of the following:

  • anti-parasitic medication
  • steroids to help control inflammation
  • pain medication for muscle aches

How to Prevent Trichinosis

According to the National Institute of Allergies and Infectious Diseases, the best way to prevent trichinosis is to make sure to cook meat to a temperature of at least 170 F (NIAID). Here are some other tips from the Centers for Disease Control for preventing trichinosis (CDC):

  • Use a meat thermometer.
  • Do not sample meat until it’s cooked.
  • Cook ground meat to at least 160 F.
  • Cook whole cuts of meat to at least 145 F.
  • Cook poultry to 165 F.
  • Freeze pork to at least 5 F.
  • Avoid eating pig, walrus, horse, or bear meat.
  • Clean any utensils that touch meat.
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