In Trichinella spiralis infection, which stage encysts in striated muscle?

• A. Adult worms in intestine
• B. Eggs
• C. Newborn larvae
• D. Merozoites

Answer: (C)

Newborn larvae are the stage that encysts in striated muscle. After Trichinella spiralis larvae are released in the small intestine and mature to adults, the female gives birth to live newborn larvae. These larvae travel through the bloodstream and invade striated muscle, where they induce the muscle cell to transform into a nurse cell and become encysted. This encysted larval form inside muscle tissue is what you find in meat. The adult worms stay in the intestine, eggs are not the encysted muscle form, and merozoites are not a part of this parasite’s muscle-encysting stage.