Parasitic Organism - Trichinella spiralis

Trichinella spiralis

Compiled By: Julie A. Albrecht, Ph.D., Associate Professor

The Organism: Trichinella spiralis is a parasitic nematode worm. The life cycle of the parasite begins when the infectious cysts are eaten with the flesh of any meat eating animal. The cysts are digested and the liberated larvae from the cysts invade the small intestine. The female hatches larvae that are carried by the blood and lymph to the muscles.

  PDF Fact Sheet

Sources of the organism:

  • Muscle tissue of infected animals

Associated foods:

  • Pork
  • Wild game (bear, moose, etc)

Organism Characteristics:

  • Parasitic roundworm nematode; needs a living host to grow.

The Disease: Trichinosis is caused by the colonization of Trichinella larvae in muscles where they grow and form cysts.

Symptoms include:

  • Diarrhea
  • Fever
  • Profuse sweating
  • Weakness
  • Muscular pain
  • Swelling around eyes

Onset time:

  • 1 day - 8 weeks

Infective Dose:

  • Consuming 1 or more cysts may cause the symptoms of the illness to develop.

Duration of symptoms:

  • Months


  • Thoroughly cook pork and wild game.
  • Proper sanitation of food contact surfaces and utensils.
  • Commercial meat processors should check with USDA for recommended procedures for quick freezing, drying and smoking to destroy the cysts.