Trichinella spiralis – the “pork worm”
Found in: Observations and pictures


Trichinella spiralis is the smallest nematode parasite in humans. It causes the disease trichinosis. It is also one of the most wide spread parasites of the world. It can be contracted by eating raw or half-cooked pork or wild game animals.

Trichinella spiralis nematode parasite

Encapsuled Trichinella spiralis larva in muscle. The larva is cut diagonally.

Trichinella spiralis nematode parasite

Longitudinal cross-section.

Trichinella spiralis nematode parasite

The larva (circular patterns) in cross-section.

Life Cycle of Trichinella spiralis

  • T. spiralis larva are encapsuled in the muscle of the host animal. The pictures on the right show different cross-sections of this stage.
  • A person who eats raw or undercooked meat will take these larva up into the body. The larvae are released by the stomach acid and pass into the intestine, where they mature and start to reproduce.
  • The offspring larvae travel in the circulatory system throughout the body and settle in the muscles, where they encyst again.


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