Life Cycle of a Trichinella

Trichinella is a species of worm that infects certain kinds of carnivorous animals including humans. Trichinella often infects domestic pigs as well. An infestation of trichinella is known as trichinellosis. The symptoms include diarrhea, vomiting, fever, headache, cough and chills. These symptoms most often begin about 1 to 2 days after the worm has entered the body.

Birth

• After mating within the body of the host animal, the female trichinella gives birth to live worms. These baby worms are very small, measuring only about .08 mm in length. They begin to look for a host cell to invade.

Larvae

• The trichinella larvae pass through the host animal’s arteries, usually ending up within the muscle tissue. In the youngest stage, the trichinella larvae have a body part known as a “stylet” that is sharp and allows it to puncture the host animal’s cells and enter them. Most of the host’s cells die as a result of this, but the skeletal muscle cells usually do not die and remain infected. The trichinella larvae go through four growth stages in about 30 hours within these cells.

Cysts

• After the young worms reach the host animal’s muscles, they curl into a ball and become hard cysts within the muscle tissue. If an animal or human eats meat that is contaminated with these trichinella cysts, its stomach acid breaks down the hard outer layer of the cysts and the worms emerge in the new host animal's body.

Adults

• Adult trichinella worms inhabit the upper part of the host animal’s small intestine. Female trichinella worms measure approximately 3 mm in length while males are smaller, measuring about 1.5 mm in length.

Mating

• The worms become sexually mature after 1 or 2 days after emerging from the cysts. Females and males mate within the host’s body and produce baby trichinella worms that then travel through the host animal's blood stream.