Anisakiasis, common in Japan, is acquired by eating raw or poorly-cooked ocean fish. Larvae burrow into the stomach and small intestine. Treatment is endoscopic removal.
CASES/YEAR
500 (US); 10,000 (Global)
OTHER NAMES
Anisakis simplex infection; Pseudoterrranova decipiens infection;
INCUBATION
Gastric: few hours; intestinal: few days to weeks; [CCDM, p. 15] 1-12 hours after ingestion of raw fish; [ID, p. 2364]
INITIAL SYMPTOMS
Abdominal pain, vomiting, and hematemesis after eating undercooked seafood; [CCDM]
PRECAUTIONS
Direct transmission from person to person does not occur. [CCDM, p. 15]
COMMENTS
In this zoonotic intestinal nematode infection, symptoms are gastric (pain and vomiting), intestinal (pain, diarrhea, and mild fever), or esophageal (difficulty swallowing). Allergic reactions include urticaria and, rarely, anaphylaxis. Humans are accidental hosts of the larvae that parasitize small crustacea, squid, octopuses, fish, and then sea mammals, the definitive hosts. [CCDM, p. 14-16] In most cases, the disease is caused by a single larva that can be removed from the mucosa of the stomach or duodenum at the time of endoscopic examination. The 2-cm-long worm may form an abscess in the wall of the esophagus, stomach, or intestines. In addition to abdominal pain and vomiting, symptoms may include mild fever, leukocytosis, eosinophilia, diarrhea, constipation, blood in the stool, and intestinal obstruction. [Guerrant, p. 781-3] Some patients have an acute illness with epigastric pain and vomiting. Others have chronic abdominal pain. The disease may resemble appendicitis, diverticulitis, or regional enteritis. [PPID, p. 3475] The worms can live in the human gut for only a few days, but they can cause an eosinophilic granuloma that may be mistaken for a gastric tumor. Cooking or freezing kill the larvae, but salting, smoking, and marinating do not. [Cecil, p. 2132]
DIAGNOSTIC
Identify larvae during gastroscopy or in surgical specimens; A skin-prick test and a serological test are available; [CCDM, p. 14]
SCOPE
Global occurrence wherever raw or inadequately processed fish consumed: Japan (sushi and sashimi); Scandinavia (graviax); South American Pacific coast (ceviche); the Netherlands (herring), and Spain (anchovies); [CCDM]
SIGNS & SYMPTOMS
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>fever
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E dysphagia
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G abdominal mass
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G abdominal pain
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G blood in stool
-
G constipation
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G diarrhea
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G hematemesis
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G nausea, vomiting
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H eosinophilia
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H leukocytosis
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R cough
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S urticaria
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*bowel obstruction
SOURCE
Animal Tissue, Eating Contaminated Food, Eating Infected or Toxin-Containing Fish, Eating Contaminated Mollusks or Crustacean
RESERVOIR
Fish and Shellfish, Wild Animals
RISK FACTORS
- Eat undercooked meat or fish
TREATMENT
Removal of larvae by endoscope or drug treatment (albendazole) may be effective. Intestinal obstruction may require endogastric suction and possible excision of lesions. [CCDM]
REFERENCES FOR CASES/YEAR
1. (US) 50 cases have been reported in North America; [ID, p. 2365] Guesstimate: Assume 1/20th of global cases/yr;
2. (Global) Most infections in Japanese and other people who eat uncooked fish and squid; [Cohen] Cases in Holland greatly decreased after compulsory treatment of herring; Cases reported in Spain related to eating raw anchovies and undercooked fish; [ID, p. 2365] About 20,000 cases were reported every year; [PMID 23092000] About 20,000 cases reported worldwide (>90% in Japan) and about 60 cases reported in US; [PMID 20804423] Guesstimate: assume now only 1/2 as many cases;