Cause
Trichinosis is caused by the larvae (immature form) of a highly versatile parasitic roundworm, Trichinella spiralis. This parasite can infect virtually every meat-eating mammal. The parasite is especially common in rats and in swine that feed on uncooked garbage.
Unlike some of the other parasitic roundworm diseases, trichinosis is not an intestinal infection in the usual sense. It is the movement of the larvae from the intestines and throughout the body and their encystment (becoming enclosed in a capsule) in muscle tissue that create serious problems.
Typically, the life cycle of the parasite follows these steps:
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A person or an animal eats contaminated meat containing parasite larvae.
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Digestive juices from the stomach dissolve the capsule-like cyst and release the larvae.
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The larvae then enter the intestine where they mature into worms and mate.
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Female worms pass larvae into the bloodstream where they make their way through the capillaries (tiny blood vessels) into the muscle fibers.
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The larvae encyst in the muscle fibers, where they can live a long time.