Anisakiasis, or herring worm disease, is a parasitic disease caused by nematodes (worms) that attach themselves to the wall of the esophagus, stomach, or intestine. The best way to prevent getting this disease is to avoid eating raw or under-cooked fish or squid.
The first case of anisakiasis in humans was described by Straub in 1955 in Holland. Since then, hundreds of cases have been reported throughout the world.
How does one become infected?
When certain infected marine mammals (such as whales or sea lions) defecate into the sea, eggs are released and become in-fective larvae while in the water. These larvae are ingested by crustaceans, which are then eaten by fish or squid. When hu-mans eat raw or undercooked infected fish or squid, they ingest nematode larvae. Once inside the human body, the larvae can invade the gastrointestinal tract. Eventually, the parasite dies and produces an inflamed mass in the esophagus, stomach, or intestine.
Some people experience a tingling sensation after - or while - eating raw or undercooked fish or squid. This actually is the worm moving in the mouth or throat. These people can often extract the worm manually from their mouth or cough up the worm and prevent infection. Also, some people experience vomiting as a symptom and this can often expel the worm from the body.
How is it diagnosed and what are the symptoms?
The diagnosis is generally made by endoscopy or surgery, if the worm has embedded itself.
The signs and symptoms of anisakiasis are abdominal pain, nausea, vomiting, abdominal distention, diarrhea, blood and mucus in stool, and mild fever. Allergic reactions with rash and itching, and infrequently, anaphylaxis can also occur.
How can I prevent anisakiasis?
Do not eat raw or undercooked fish or squid.
The recommendation for seafood preparation or storage to kill parasites is:
Cooking (Seafood in General)
- Cook seafood adequately (to an internal temperature of at least 145°F [~63° C]).
- At -4°F (-20°C) or below for 7 days (total time), or
- At -31°F (-35°C) or below until solid, and storing at -31°F (-35°C) or below for 15 hours, or
- At -31°F (-35°C) or below until solid and storing at -4°F (-20°C) or below for 24 hours.
What is the treatment?
The treatment for anisakiasis may require removal of the worm from the body by endoscopy or surgery.