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Trichinosis

A roundworm (Trichinella spiralis) infestation, usually transmitted by eating raw or undercooked pork which contains cysts of Trichinella spiralis. It is not an uncommon infection worldwide.

The muscle of infected animals contain cysts that, when ingested, hatch within the human intestinal tract to produce an adult roundworm. The adult then produces numerous larvae that migrate through the gut wall and bloodstream to muscle tissue, where they form cysts. The cyst form is part of the parasite's life cycle in which the tissue is eaten and the parasite is passed on to the next animal. Humans are an end host for the parasite because T. spiralis encysted in human muscle will never be eaten.

Early symptoms of infestation with T. spiralis are usually gastrointestinal -- cramping and diarrhoea can occur. The larvae migrate to muscle, where they cause an inflammatory reaction that produces muscle pain (myalgia). Pain is most notable on movement and in muscles that are constantly in motion (the breathing muscles such as the diaphragm and rib muscles) can be very painful. During migration of the larvae through tissue, the infected person often develops swelling in the face and around the eyes. Larvae can invade the muscle of the heart and cause erratic heart rhythm (arrhythmias) or damage to the heart muscle.

PREVENTION
Pork and meat from wild animals should be cooked until well done. Freezing at subzero temperatures) for 3 to 4 weeks will kill the encysted organism.

SIGNS AND TESTS
- FBE (increased eosinophils)
- muscle biopsy (trichinella cysts present in the muscle)
- serology studies (Bentonite flocculation test positive for trichinella)
- CPK (may show elevated levels of creatine kinase)

TREATMENT
There is no specific treatment for trichinosis once the larvae have invaded the muscles. Analgesics can relieve the muscle pain.
Severity of trichinosis depends on how heavily the individual is infested. Light infestations may go unnoticed. Heavier infestations may cause severe symptoms. Very heavy infestations may result in heart failure.