Pruritus Ani
Type: Symptom
Definition
Intense itching localized to the skin immediately surrounding the anus.
Clinical Details
This is the hallmark symptom of enterobiasis, caused directly by the nocturnal migration of female worms to the perianal folds. The mechanical movement of the worm and the sticky, allergenic fluid she secretes to adhere her eggs trigger a massive local hypersensitivity response. The itching is typically worse at night, compelling the host to scratch the area.