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What Is Trichinosis?

Trichinosis, also known as trichinellosis, is a disease caused by a species of roundworm called Trichinella. These parasitic roundworms are found in animals that eat meat, such as:

  • pigs
  • bears
  • foxes
  • walruses
  • wild boars

You can contract trichinosis if you eat raw or undercooked meat from an animal infected with Trichinella. The most common offending agent for humans is pork meat. The roundworm begins its life cycle in the intestines and then lodges itself in the muscles, causing pain and discomfort.

According to the Centers for Disease Control and Prevention, approximately 10,000 cases of trichinosis are diagnosed every year around the world. Trichinosis is fairly rare in the United States since there are strict laws for meat processing and animal feed. In fact, an average of only 400 trichinosis cases are reported each year in the United States. The disease is most commonly seen in rural areas.

What Are the Symptoms of Trichinosis?

When you first become infected, you may or may not have any symptoms. However, within one week of the initial infection, the larvae will enter your muscle tissue. Once this happens, the symptoms usually become apparent.

Trichinosis symptoms that may occur while the larvae are in your intestines include:

  • diarrhea
  • abdominal cramps
  • fatigue or low energy
  • nausea
  • vomiting

Trichinosis symptoms that may occur after the larvae enter your muscle tissue include:

  • muscle aches and pains
  • a high fever
  • facial swelling
  • sensitivity to light
  • persistent eye infections
  • unexplained rashes
  • headaches
  • chills

What Causes Trichinosis?

Trichinosis is caused by the larvae of the Trichinella roundworm. The parasitic worm is often found in animals that eat meat. Pigs are one of the most common carriers of this parasite. The Trichinella roundworm is also commonly found in bears, foxes, and wild boars. Animals can become infected with Trichinella when they feed on other infected animals or on garbage containing infected meat scraps.

Humans can contract trichinosis when they eat raw or undercooked meat of an animal infected with Trichinella larvae. After the parasites are ingested, the acid in the stomach dissolves the cyst, which is the protective capsule surrounding the larvae. When the hard covering of the cyst is dissolved, the larvae enter the intestine, where they mature into adult worms and reproduce. The female worms then release their larvae into the bloodstream, allowing them to migrate through the blood vessels and into the muscles. Once they’re in the muscles, the worms encapsulate into the muscle tissues, where they can live for an extended period.

How Is Trichinosis Diagnosed?

Your doctor may be able to diagnose trichinosis by taking your medical history and asking you about your symptoms. They may also perform certain diagnostic tests to determine whether there any larvae present in your system.

Your doctor may take a sample of your blood and test it for signs of trichinosis. Elevated levels of white blood cells and the presence of antibodies against the parasite may indicate a Trichinella infection.

Your doctor may also perform a muscle biopsy if the blood test results are inconclusive. During a muscle biopsy, your doctor will remove a small piece of muscle tissue and analyze it for the presence of Trichinella larvae.

How Is Trichinosis Treated?

Trichinosis doesn’t always require treatment. The infection may resolve without treatment within several months after the onset of symptoms. However, the condition is often treated with medications to help manage symptoms and to prevent complications from developing. Your doctor may prescribe antiparasitic medication (albendazole or mebendazole usually) to treat the infection, steroids to help control inflammation, and pain medication for muscle aches.

What Are the Potential Complications of Trichinosis?

In rare cases, a severe Trichinella infection could lead to the following complications:

  • myocarditis, which is an inflammation of the heart muscle
  • encephalitis, which is an inflammation of the brain tissue
  • meningitis, which is an inflammation of the membranes around the brain and spinal cord
  • bronchopneumonia, which is an inflammation of the lungs and airways
  • nephritis, which is a condition that causes the kidney to become inflamed
  • pneumonia, which is a lung infection that causes the air sacs in the lungs to become inflamed
  • sinusitis, which is a sinus infection that causes the sinuses and nasal passages to become inflamed

Though some of these conditions can be serious, they’re often detected during diagnostic testing, so treatment can be received fairly quickly.

What Is the Outlook for People with Trichinosis?

The outlook for people with trichinosis is generally good. Trichinosis usually isn't a serious condition and may go away without treatment within a few months. However, receiving prompt treatment can speed up your recovery and prevent complications. This can improve your outlook.

Certain symptoms may linger for an extended period, even after treatment. Symptoms that may persist include fatigue, mild muscle pain, and diarrhea. Talk to your doctor if you have any concerns about symptoms you may be continuously experiencing after treatment.

How Can Trichinosis Be Prevented?

The best way to prevent trichinosis is to prepare food properly. Here are some tips to follow when cooking meat:

  • Use a meat thermometer.
  • Don’t sample meat until it’s cooked.
  • Cook ground meat and wild game to at least 160°F (71°C).
  • Cook whole cuts of meat to at least 145°F (63°C).
  • Cook poultry to at least 165°F (74°C).
  • Freeze pork less than 6 inches thick for 20 days at 5°F (-15°C) to kill any worms.
  • Avoid eating walrus, horse, or bear meat.
  • Thoroughly clean any utensils that touch meat.
  • Clean meat grinders thoroughly.
  • Wash hands thoroughly after handling raw meat.

To prevent a Trichinella infection among animals, don’t allow pigs or wild animals to eat the undercooked meat, scraps, or carcasses of animals that may be infected with Trichinella larvae.

Content licensed from:

Written by: Shannon Johnson
Medically reviewed on: Feb 25, 2016: Steve Kim, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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