Pinworm

Human gastrointestinal tract, primarily the large intestine and rectum; eggs can survive on surfaces like bedding, clothing, and toys.

Content of the human host's intestine; they do not feed on blood or tissue.

Nocturnal migration where gravid females travel to the perianal area to deposit eggs; eggs become infectious within hours and are spread via the fecal-oral route.

Risks include intense itching (pruritus ani), secondary bacterial infections from scratching, and irritability. They provide no known ecological benefits and are considered a common human parasite.