(Herring Worm Disease; Cod Worm Disease; Seal Worm Disease)
(See also Approach to Parasitic Infections.)
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 such as Japan, Korea, and other areas where raw fish is traditionally consumed. Larvae burrow into the stomach and small bowel of humans. Commercial sushi prepared in the United States and elsewhere where fish is frozen under conditions that kill anisakid larvae is safe.
Symptoms of gastric anisakiasis typically include abdominal pain, nausea, and vomiting within hours of ingesting the larvae. Involvement of the small intestine is less common and may result in an inflammatory mass and subacute symptoms resembling Crohn disease that develop 1 to 2 weeks later. Ectopic infections outside the lumen of the gastrointestinal tract may rarely occur.
Anisakiasis typically resolves spontaneously after several weeks; rarely, it persists for months.
Proper freezing conditions are key to preventing anisakiasis in sushi. Anisakis larvae are destroyed by
Larvae may resist pickling, salting, and smoking.
Humans acquire Anisakis when they consume the intermediate hosts (fish or squid) that are raw or undercooked; thus, anisakiasis is common in Japan and other cultures where raw fish is traditionally consumed.
Anisakiasis typically causes abdominal pain, nausea, and vomiting within hours of ingesting the larvae; an inflammatory mass may form in the small intestine and symptoms may resemble Crohn disease.
Anisakiasis typically resolves spontaneously after several weeks.
Do upper endoscopy to diagnose anisakiasis.
Endoscopic removal of the larvae is curative.
Proper freezing conditions prevent anisakiasis in sushi.