Trichiniasis

Alternative names
Trichinosis; Trichinellosis

Definition
Trichinosis is a roundworm (Trichinella spiralis) infection, usually contracted by eating raw or undercooked meat.

Causes, incidence, and risk factors

Trichinosis is a parasitic disease that results from eating undercooked meat, most frequently pork, which contains cysts of Trichinella spiralis. T. spiralis can be found in pork, bear, fox, rat, horse and lion meat.

Trichinosis is a common infection worldwide, but it is seldom seen in the United States because of regulations regarding the feeding of domestic animals and meat-processing inspections.

When a person eats meat from an infected animal, trichinella cysts hatch in the intestines and grow into adult roundworms, which measure 2-4 mm long.

The roundworms then produce offspring that migrate through the gut wall and into the bloodstream. These parasites tend to invade muscle tissues, including the heart and diaphgragm (the breathing muscle under the lungs). They can also affect the lungs and brain.

Domestic meat animals (hogs) raised specifically for consumption under USDA guidelines and inspection can be considered safe. Wild animals, especially carnivores (meat eaters) or omnivores (animals that eat both meat and plants), should be considered a possible source of roundworm disease.

There are approximately 40 cases per year in the US.

Risk factors include eating meat from wild game.

Symptoms

     
  • History of having eaten rare or uncooked pork (bear and other wild carnivores or omnivores)  
  • Abdominal discomfort  
  • Cramping  
  • Diarrhea  
  • Muscle pain (especially muscle pain with breathing, chewing, or using large muscles)  
  • Fever

Signs and tests

     
  • CBC (increased eosinophils)  
  • Muscle biopsy (trichinella cysts are seen in the muscle)  
  • Serology studies  
  • CPK (may show elevated levels of muscle enzymes)

Treatment
There is no specific treatment for trichinosis once the larvae have invaded the muscles. Albendazole can work on the intestinal forms, but not on the muscle forms. Analgesics can relieve the muscle pain.

Expectations (prognosis)
Most people with trichinosis have no symptoms and their infection is self-limited (resolves on its own). More severe infections may be more difficult to treat, especially if the lungs, the heart, and/or the brain is involved.

Complications

     
  • Arrhythmias from heart inflammation (myocarditis)  
  • Heart failure  
  • Encephalitis  
  • Pneumonia

Calling your health care provider
Call your health provider if you have symptoms suggestive of trichinosis and a recent history of eating undercooked or raw meat that might have been contaminated.

Prevention
Pork and meat from wild animals should be cooked until well done. Freezing at subzero temperatures (Fahrenheit) for 3 to 4 weeks will kill the organism. Smoking, salting, or drying meat are not reliable methods of preventing this infections.

Johns Hopkins patient information

Last revised: December 7, 2012
by Sharon M. Smith, M.D.

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