Scombroid Fish Poisoning
Scombroid fish poisoning is a syndrome resembling an allergic reaction that occurs within a few hours of eating fish contaminated with histamine. There are no specific diagnostic tests for scombroid fish poisoning in humans, and diagnosis is generally made based on symptoms and recent dietary history.
Illness typically begins minutes to hours after ingestion of the toxic fish and resembles a histamine reaction. Associated symptoms include tingling and burning sensations around the mouth, facial flushing and sweating, nausea, vomiting, headache, palpitations, dizziness, and rash. Some patients report that the implicated fish has a peppery or a metallic taste.
Fish in the Scombridae family (tuna, mackerel, skipjack and bonito) are the most common vehicles for scombroid fish poisoning. Other fish, however, have been implicated in scombroid fish poisoning, and include mahi mahi, bluefish, marlin, and escolar. When susceptible fish are not promptly and continuously refrigerated, bacteria can metabolize naturally occurring histimine to produce scombrotoxin, which consists of histamine and other amines. The presence of 50 parts per million (ppm) or more histamine in fish is indicative of decomposition whether or not there is gross evidence of spoilage, such as bad odor. When illness results, histamine levels in implicated fish have commonly been at least 200 ppm and often greater than 500 ppm. Histamine is heat resistant and can, therefore, cause illness even when fish is properly canned or cooked thoroughly. While some contaminated fish will not show any outward signs of spoilage, others will show such signs as a bad odor. Cooked fish that has spoiled may have a "honey combed" appearance.
Scombroid fish poisoning is usually mild and duration is short, making treatment unnecessary. For more severe cases or in patients with underlying medical conditions, oral antihistamines may be beneficial.
What can a person do to prevent scombroid fish poisoning?
- Fish should be appropriately refrigerated from the time of capture to the time cooked.
- Fish with a bad odor or a "honey-combed" appearance should not be consumed.
- If scombroid fish poisoning is suspected, suspected fish should be saved for laboratory analysis.