Final answer:
The human pinworm, Enterobius vermicularis, resides in the colon of humans and is the most common nematode causing enterobiasis, especially among children in the U.S.
Step-by-step explanation:
The human pinworm Enterobius vermicularis lives in the colon of humans. This organism is a type of nematode, more commonly known as a pinworm, and it is responsible for causing the condition known as enterobiasis. Pinworm infections are highly prevalent in the United States, particularly among children. These tiny (2–13 mm) roundworm parasites are ingested as nearly microscopic eggs and later hatch and mature in the human digestive tract. The female pinworms typically exit the body and lay their eggs at night, causing an itching sensation around the anus. This itching can lead to re-infection or further spread of the parasite when eggs lodged under the fingernails of the infected individual are transferred to their mouth or onto surfaces that others might touch.