Pinworm

The primarily habitat is the human gastrointestinal tract, specifically the large intestine and rectum.

They feed on intestinal contents and mucosal secretions within the human host.

Female worms migrate out of the anus at night to deposit thousands of eggs on the surrounding skin, which often causes intense itching (pruritus ani). Infection occurs via the fecal-oral route.

Risks include intense itching, disturbed sleep, and irritability. While generally not dangerous, heavy infestations can lead to secondary skin infections from scratching. They provide no known benefits to the host.