Life Cycle of Ascaris Suum

Ascaris suum is the proper name of a parasitic roundworm of pigs. This worm has also been known to parasitize humans. The life cycle can be direct or indirect depending on the species and route of infection.

  1. Infection

    • The pig ingests eggs that are in the environment. In the eggs, the immature ascaris larvae have already matured to stage 2. The eggs are hard shelled and extremely durable in the environment.

    Development

    • After ingestion, the larvae complete development to stage 3 in the liver. It is at this stage that they begin migration to the lungs. Here, they infect the alveoli and induce coughing, which facilitates the migration from the lungs back to the digestive tract.

    Maturation

    • The larvae undergo two more stages of development in the small intestine and are then mature adults. The process begins again as the adult worms mate and release eggs into the digestive tract, which are then released into the environment through the feces.

    Indirect Infection

    • The eggs can also be eaten by a nonprimary host such as a beetle or earthworm, where they remain dormant until eaten by a pig.

    Symptoms

    • Symptoms of infection include coughing; rapid, shallow breathing; weight loss; and lethargy.