Trichinosis is infection with the roundworm Trichinella spiralis.
Causes, incidence, and risk factors
Trichinosis is a disease caused by eating meat that has not been thoroughly cooked and contains cysts (larvae, or immature worms) 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 possible sources of roundworm disease. Domestic meat animals raised specifically for eating under United States Department of Agriculture (government) guidelines and inspection can be considered safe. For this reason, cases of trichinosis are rare in the United States though it is a common infection worldwide.
When a person eats meat from an infected animal, Trichinella cysts break open in the intestine and grow into adult roundworms. The roundworms produce other worms that move through the gut wall and into the bloodstream. The worms invade muscle tissues, including the heart and diaphragm (the breathing muscle under the lungs). They can also infect the lungs and brain. The cysts remain alive for years.
- Abdominal discomfort
- Facial swelling around the eyes
- 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
- Antibody test from the blood (serology)
Medicines such as mebendazole or albendazole can be used to treat infections in the intestines though mild infection does not usually need treatment. Pain medicine can help relieve muscle soreness after the larvae have invaded the muscles.
Most people with trichinosis have no symptoms and the infection goes away by itself. More severe infections may be difficult to treat, especially if the lungs, heart, or brain is involved.
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.
Pork and meat from wild animals should be cooked until well done (no traces of pink). Freezing pork at subzero temperatures (Fahrenheit) for 3 to 4 weeks will kill the organism. Freezing wild game meat does not always kill the worms. Smoking, salting, and drying meat are not reliable methods of killing the worms either.
Diemert DJ. Tissue nematode infections. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011: chap 366.
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. Philadelphia, PA: Elsevier Churchill-Livingstone; 2009:chap 288.
Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.