Trichinella spiralis

Trichinella spiralis is a nematode parasite, occurring in rats, pigs, and humans, and is responsible for the disease trichinosis. It is sometimes referred to as the "pork worm" due to it being found commonly in pork or rat products that are undercooked.Trichinella species are the smallest nematode parasite of human, which has an unusual life cycle and one of the most widespread and clinically important parasites in the world. The small adult worms mature in the intestine of an intermediate host such as a pig. Each adult female produces batches of live larvae, which bore through the intestinal wall, enter the blood (to feed on it) and lymphatic system, and are carried tostriated muscle Once in the muscle, they encyst, or become enclosed in a capsule. Humans can be infected by eating infected pork or wildcarnivores such as fox, cat or bear.

Trichinella spiralis is a parasitic nematode that has a direct life cycle, meaning that it completes all stages of development in one host. The larval forms of T. spinalis are encapsulated as a small cystic structure within the infected host. Human typically become infected when they eat improperly cooked pork or Trichinella infected meat. When a human eats the infected meat, the larvae are released from the nurse cell (due to stomach pH) and migrate to the intestine where they burrow into the intestinal mucosa, mature, and reproduce . Interestingly, juveniles within nurse cells have an anaerobic or facultative anaerobic metabolism but when they become activated adopt an aerobic metabolism characteristics of the adult.

The first symptoms may appear between 12 hours and two days after ingestion of infected meat. The migration of worms in the intestinal epithelium can cause traumatic damage to the host tissue and the waste products they excrete can provoke an immunological reaction. The resulting inflammation can cause symptoms such as nausea, vomiting, sweating and diarrhea. Five to seven days after the appearance of symptoms facial edema and fever may occur. After 10 days intense muscular pain, difficulty breathing, weakening of pulse and blood pressure, heart damage and various nervous disorders may occur, eventually leading to death due to heart failure, respiratory complications or kidney malfunction.

Muscle biopsy is used for trichinosis detection. Several immunodiagnostic tests are also available. Typically patients are treated with either Mebendazole or Albendazole but efficacy of such products are uncertain. Symptoms can be relieved by use of analgesics and corticosteroids.