Anisakiasis of the colon presenting as bowel obstruction.

Anisakiasis is a disease caused by human infection by the Anisakis larvae, a marine nematode found in raw or undercooked fish. With the increased popularity of eating sushi and raw fish (sashimi) in the United States infection with anisakis is expected to rise. We present the first reported case in the United States of intestinal anisakiasis presenting as a bowel obstruction. A 25-year-old healthy woman with no prior history of surgery presented to the emergency room with bowel obstruction by history and CT. CT also showed a mass in the right lower quadrant. She had eaten seviche, a raw fish appetizer, 2 days earlier and sashimi 3 weeks before admission. She was taken to the operating room for an exploratory laparotomy and was found to have an obstruction, the 2-cm mass in the mesentery, and diffuse mesenteric adenopathy. She had an ileocolectomy. Pathology showed a degenerating fish worm, anisakiasis. She also had a serologic test for immunoglobulin E specific to anisakiasis and it was highly positive. Human infections, as mentioned before, are principally the result of ingestion of the Anisakis larvae. These larvae are usually found in herring, mackerel, salmon, cod, halibut, rockfish, sardine, and squid. Most human infections have been reported from Japan and The Netherlands and involve the stomach. Invasion of the gastric or intestinal wall one to 5 days after eating raw fish may be characterized by the abrupt onset of abdominal pain, nausea and/or vomiting, diarrhea, or an ileus. For transient anisakiasis, supportive measures and reassurance are all that is needed. If the larvae have invaded the intestine or the stomach wall diagnosis and cure occur with endoscopic or surgical removal if evidence of obstruction or perforation is found. The incidence of anisakiasis in the United States is unknown but will likely continue to increase with the popularity of eating sashimi. This case is meant to demonstrate another possible cause for bowel obstruction in the patient who has just eaten raw or undercooked fish.