Accidental endoscopic finding of Anisakis simplex in human colon

Anisakidosis is a zoonotic disease caused by the ingestion of nematodes belonging to the family of Anisakidae. Human infection is caused by intake of raw or undercooked sea fish and cephalopods infested by Anisakis larvae. We present a case of accidental endoscopic finding of an alive nematode adhering to distal ascending colon in a 32 years old man, submitted to colonoscopy owing to recent onsets of rectal bleeding of likely hemorrhoidal origin. The nematode, removed from colon by means of biopsy forceps, has been identified as L3 larvae of A. simplex by a light microscope. Histological examination of intestinal mucosa showed a mild fibrosis of lamina propria, characterized by focal lymphocytic inflammation and scattered infiltration of eosinophils. The patient reported the intake of marinated anchovies 3 days before endoscopic examination.