Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 35-31: Anisakiasis + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Nausea, vomiting, and progressive epigastric pain Occasionally, acute infection is followed by a chronic course Infection is by larval invasion of the stomach or intestinal wall by anisakid nematodes +++ General Considerations ++ Caused by infection with larvae of parasites of saltwater fish and squid Multiple species of the family Anisakidae may occasionally infect humans Definitive hosts for these parasites are marine mammals Eggs are passed in the feces and ingested by crustaceans, which are then eaten by fish and squid When ingested by humans in undercooked seafood, larvae penetrate the stomach or intestinal wall but cannot complete their life cycle +++ Demographics ++ Most common in Japan + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Clinical manifestations follow burrowing of worms into the stomach or intestinal wall, leading to Localized ulceration Edema Eosinophilic granuloma formation Acute infection Causes severe epigastric or abdominal pain, nausea, and vomiting (usually within 2 days of parasite ingestion) May cause allergic symptoms (eg, urticaria, angioedema, and anaphylaxis) Generally resolves within 2 weeks Chronic symptoms suggest Inflammatory bowel disease Diverticulitis Carcinoma Rarely, worms may migrate to other sites or be coughed up +++ Differential Diagnosis ++ Norwalk virus or rotavirus "Food poisoning" by toxins from Bacillus cereus, Staphylococcus aureus, Clostridium perfringens Appendicitis Peptic ulcer disease or gastritis Inflammatory bowel disease + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Eosinophilia is not usually seen +++ Imaging Studies ++ Radiographs may identify stomach or intestinal lesions +++ Diagnostic Procedures ++ Diagnosis is suggested in persons with acute abdominal symptoms after eating raw fish Endoscopy may allow visualization and removal of the worm + Treatment Download Section PDF Listen +++ +++ Medications ++ Specific therapy is not indicated +++ Surgery ++ When surgery is performed due to consideration of other diagnoses, eosinophilic inflammatory lesions and invading worms are found +++ Therapeutic Procedures ++ Endoscopic worm removal hastens recovery Parasites are killed by cooking or deep freezing fish + Outcome Download Section PDF Listen +++ +++ Complications ++ Chronic intestinal anisakiasis +++ When to Refer ++ Refer for consideration of mechanical removal of the worm +++ Prevention ++ Avoidance of ingestion of raw or incompletely cooked squid or marine fish, especially salmon, rockfish, herring, and mackerel; early evisceration of fish is recommended Larvae within fish may, with difficulty, be seen as colorless, tightly coiled or spiraled worms in 3-mm whorls or as reddish or pigmented larvae lying open in muscles or viscera The larvae are killed by temperatures above 60°C or by freezing at –23°C for 7 days or at –35°C for 15 hours Smoking procedures that do not bring the temperature to 60°C, marinating in vinegar, and salt-curing are not reliable + Reference Download Section PDF Listen +++ + +Sohn WM et al. Anisakiasis: report of 15 gastric cases caused by Anisakis type I larvae and a brief review of Korean anisakiasis cases. Korean J Parasitol. 2015 Aug;53(4):465–70. [PubMed: 26323845]