Definition of Trichinosis:

Trichinosis is infection with the roundworm Trichinella spiralis.

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.