Trichina encysted in muscle—Russ Kinne/Photo Researchers

Species (Trichinella spiralis) of parasitic nematode, found worldwide, that causes the disease trichinosis. Trichinae (or trichinas), 0.06–0.2 in. (1.5–4 mm) long, mate in the host's small intestine. Fertilized females penetrate the intestinal wall and release larvae, which the blood carries throughout the body. The larvae grow, mature, and become encysted within muscle tissue. The digestive juices of an animal that eats the muscle tissue break down the cyst, liberating the larvae for further development; the worms mature, and the cycle begins again.

This entry comes from Encyclopædia Britannica Concise.
For the full entry on trichina, visit

Seen & Heard

What made you look up trichina? Please tell us what you were reading, watching or discussing that led you here.