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Colonic Anisakiasis

Colonoscopic view of a mobile polypide in the ileocecum.

Colonoscopic view of a mobile polypide in the ileocecum.

To the Editor:

A 24-year-old man with a 2-week history of nausea, lower-right abdominal pain, and melena presented to the Gastroenterology outpatient clinic. He had no previous cardiovascular or gastrointestinal problems and denied any history of an allergy. In addition, the patient reported having eaten raw mackerel, sardines, and squid at a sushi restaurant 2 weeks prior to symptom onset. His vital signs were normal. On physical examination, he exhibited mild tenderness of his right lower abdomen without guarding or rebound tenderness. The complete blood examination, including an eosinophil count and blood chemistry, was unremarkable. A simple radiograph showed no abnormality. Colonoscopy revealed a live tortuous polypide in the ileocecum (Figure). The polypide was successfully removed using endoscopic forceps. The patient’s abdominal pain resolved soon after the procedure. Based on the clinical history and histopathological findings, the patient was diagnosed as having colonic anisakiasis. Anisakiasis, in humans, is a well-known parasitic disease resulting from the accidental ingestion of raw fish infected with larvae belonging to the family Anisakidae.1 Most cases of anisakiasis involve the stomach with acute symptoms, including sudden abdominal pain, nausea, vomiting, and anaphylaxis. However, colonic anisakiasis is very rare, and only a few cases have been reported.23 However, as the Japanese style of eating fish, such as “sushi” and “sashimi,” has increased in popularity, the consumption of raw fish has increased globally. Therefore, the number of cases of this parasitic disease may increase throughout the world.

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-Hiroki Matsuura, MD, Hideki Jinno, MD

This article originally appeared in the May issue  of The American Journal of Medicine.

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