Trichinosis is a parasitic infection by the roundworm Trichenella spiralis. People can swallow the cysts of roundworm larvae (immature worm surrounded by a hard capsule) when eating infected raw or undercooked meat. The larvae cysts are most likely to be found in wild meat like bear, fox, horse, or walrus. Undercooked pork from domestic pigs may also be a source of the parasite though farming regulations in many countries have decreased such infections. Around the world, trichinosis infections are more common in rural areas. Trichinosis cannot be passed from person to person.
When the larvae cysts enter the stomach, stomach acids release the larvae. The larvae grow into adult worms in the small intestine. The adult worms produce eggs which grow into larvae and then travel through the arteries (blood vessels) to the muscles. The larvae again make hard capsules around themselves (cysts). The cycle only continues if the raw or undercooked muscle meat is eaten by another animal.
If only a few larvae cysts are in the meat which is eaten, symptoms will be mild. If more cysts are present, early symptoms (1-2 days after infection) may include stomach pain, tiredness, nausea, diarrhea, and vomiting. When the new larvae move to the muscles (between 2-8 weeks), symptoms may include a high fever, facial swelling, weakness, muscle pain, headache, light sensitivity, and pink eye. Severe, large infections are rare but can lead to heart, brain, and lung inflammation.
Blood tests and muscle biopsy may be used for diagnosis. Treatment with medication should begin as soon as possible to avoid muscular pains and symptoms. Trichinosis infection is preventable by avoiding undercooked meat, especially wild game and poultry. Irradiation will also kill the larvae cysts. Microwaving, pickling, curing or smoking meat will not. If you have been diagnosed with trichinosis, talk to your doctor about the most current treatment options.