Trichinella spiralis: The worm that causes trichinosis. Trichinella spiralis larvae can infest pigs and wild game, hibernating in muscle tissue within a protective cyst.
Trichinosis can be correspondingly defined as a disease caused by eating raw or undercooked pork or wild game infested with the larvae of the worm Trichinella spiralis.
When a human or an animal eats meat that contains infective Trichinella cysts, the acid in the stomach dissolves the hard covering of the cyst and releases the worms. The worms pass into the small intestine and, in 1-2 days, become mature. After mating, adult females lay eggs. Eggs develop into immature worms, travel through the arteries, and are transported to muscles. Within the muscles, the worms curl into a ball and encyst (become enclosed in a capsule). Infection occurs when these encysted worms are consumed in meat.