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by Richard D. Pearson, MD

Anisakiasis is infection with larvae of worms of the genus Anisakis and related genera such as Pseudoterranova. Infection is acquired by eating raw or poorly cooked saltwater fish; larvae burrow into the mucosa of the GI tract, causing discomfort.

Anisakis is a parasite that resides in the GI tract of marine mammals. Excreted eggs hatch into free-swimming larvae, which are ingested by fish and squid; human infection is acquired by ingestion of these intermediate hosts in a raw or undercooked state. Thus, infection is particularly common in locations and cultures in which raw fish is traditionally consumed. Larvae burrow into the stomach and small bowel.

Symptoms typically include abdominal pain, nausea, and vomiting; intestinal infection may create an inflammatory mass causing symptoms resembling Crohn disease.


  • Upper endoscopy

Diagnosis is usually made by upper endoscopy; stool examination is unhelpful, but a serologic test is available in some countries. Infection typically resolves spontaneously after several weeks; rarely, it persists for months. Endoscopic removal of the larvae is curative.


  • Albendazole

Treatment with albendazole 400 mg po bid for 3 to 5 days may be effective.


Larvae are destroyed by

  • Cooking to > 63° C (> 145° F)

  • Freezing at -20° C (-4° F) or below for 7 days

  • Freezing at -35° C (-31° F) or below until solid, then storing at that temperature for ≥ 15 h, or at -20° C (-4° F ) for 24 h

Larvae may resist pickling, salting, and smoking.

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