Trichinosis

Definition

Trichinosis is infection with the roundworm Trichinella spiralis.

Alternative Names

Trichiniasis; Trichinellosis

Causes, incidence, and risk factors

Trichinosis is a disease caused by eating undercooked meat containing cysts of Trichinella spiralis. Trichinella spiralis can be found in pork, bear, walrus, fox, rat, horse, and lion meat.

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

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

When a person eats meat from an infected animal, Trichinella cysts break open in the intestines and grow into adult roundworms.

The roundworms produce other worms that move through the gut wall and into the bloodstream. These organisms tend to invade muscle tissues, including the heart and diaphragm (the breathing muscle under the lungs). They can also affect the lungs and brain.

There are approximately 40 cases of trichinosis each year in the U.S.

Symptoms

• Abdominal discomfort
• Cramping
• Diarrhea
• Facial swelling around the eyes
• Fever
• Muscle pain (especially muscle pain with breathing, chewing, or using large muscles)
• Muscle weakness

Signs and tests

The patient may have a history of having eaten rare or uncooked pork, horsemeat, or wild game. Tests to diagnose this condition include:

• Complete blood count (CBC)
• Eosinophil count
• Creatine kinase level (an enzyme found in muscle cells)
• Muscle biopsy

Treatment

Mebendazole or albendazole can be used to treat infections in the intestines. There is no specific treatment for trichinosis once the larvae have invaded the muscles. The cysts remain viable for years. Pain killers can help relieve muscle soreness.

Support Groups

Expectations (prognosis)

Most people with trichinosis have no symptoms and the infection goes away by itself. More severe infections may be more difficult to treat, especially if the lungs, the heart, or the brain is involved.

Complications

• Encephalitis
• Heart failure
• Heart rhythm problems (arrhythmias) from heart inflammation (myocarditis)
• Pneumonia

Calling your health care provider

Call your health provider if you have symptoms of trichinosis and recently ate undercooked or raw meat that might have been contaminated.

Prevention

Pork and meat from wild animals should be cooked until well done (no traces of pink). Freezing at subzero temperatures (Fahrenheit) for 3 to 4 weeks will kill the organism. Smoking, salting, or drying meat are not reliable methods of killing the organism that causes this infection.

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References

Kazura JW. Nematode infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 378.

Kazura JW. Tissue nematodes including trichinellosis, dracunculiasis, and the filariases. In: Mandell GL, Bennett JE, Dolan R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Orlando, FL: Saunders Elsevier; 2009:chap 288.