Pinworm

The human large intestine (specifically the cecum and appendix); eggs are found in the perianal area and contaminated environments.

Intestinal contents, bacteria, and epithelial cells within the human digestive tract.

Nocturnal migration where gravid females move to the perianal region to deposit eggs, causing itching. Eggs become infectious within hours and are spread via the fecal-oral route.

Causes enterobiasis, characterized by intense anal itching and restless sleep. While generally not dangerous, it is highly contagious and requires medical treatment (anthelmintics) for the patient and household.