Scombroid fish poisoning (SFP), the most common fish-related illness worldwide, is a histamine response caused by the heat stable toxin histamine.[1] Scombroid or histamine food poisoning (scombrotoxism, scombroid ichthyotoxicosis) is a foodborne illness resulting from ingestion of Scombroidea fish (tuna, mackerel, albacore, bonito) or non-scombroid fish (mahimahi, amberjack, bluefish, herring, anchovies, sardines) undergoing bacterial decomposition and cheeses that contain unusually high levels of histamine. Scombroid fish poisoning (SFP) is a histamine response caused by the ingestion of histamine, a heat stable toxin.
How do people get scombroid fish poisoning?
Scombroid fish poisoning is caused by eating fish that contain high levels of histamine. Bacteria convert histidine, an essential amino acid found in the flesh of the fish, to histamine. The process of histidine conversion can be mitigated by inhibiting bacterial growth through proper storage of freshly caught fish by refrigeration or icing. Conversely, when fish are improperly stored after capture, bacterial overgrowth can occur, facilitating and accelerating histamine production.[2] One of the most common fish poisonings, scombroid occurs worldwide in both temperate and tropical waters. Fish typically associated with scombroid have naturally high levels of histidine in their flesh and include amberjack, anchovies, bluefish, herring, mackerel, mahi mahi (dolphin fish), marlin, sardines, and tuna. Histamine and other scombrotoxins are resistant to canning, cooking, freezing, and smoking.
What are the typical symptoms of scombroid fish poisoning?
Scombroid poisoning is frequently misdiagnosed because it can so closely resemble a severe food allergic reaction (anaphylaxis). Symptoms usually appear 10–60 minutes after a person eats contaminated fish. Signs and symptoms include abdominal cramps and diarrhea, blurred vision, flushing of the face and upper body resembling sunburn, severe headaches, itching, and palpitations. Id. One of the differentiating factors between the urticarial rash of scombroid poisoning and allergy is the lack of wheals (patchy areas of skin swelling typically known as hives).[3] [4] Scombroid poisoning usually responds well to antihistamines. Left untreated, symptoms usually resolve within 12 hours but can last up to 48 hours. Rarely, respiratory compromise, malignant arrhythmias, and hypotension requiring hospitalization can occur. Scombroid poisoning is not an allergic reaction, and fish consumption does not have to be withheld.[5]
Prevention and treatment of scombroid fish poisoning
According to the CDC, fish contaminated with histamine can have a peppery, sharp, or salty taste or a “bubbly” feel, but will usually look, smell, and taste normal. The key to prevention is to make sure fish are properly iced or refrigerated at temperatures <38°F (<3.3°C) or immediately frozen after being caught. However, scombroid poisoning can occur after consumption of fresh or canned fish—canning, cooking, freezing, or smoking will not destroy histamine in contaminated fish. When these fish are not properly refrigerated and stored along the supply chain, either in the boat that caught them, the processing factory or the store that sold them, histidine undergoes gram‑negative bacterial conversion to histamine (i.e., Clostridium perfringens, Escherichia coli, Klebsiella, Pseudomonas aeruginosa, Morganella morganii, Morganella psychrotolerans, Hafnia alvei) in the fish’s intestines following time temperature abuse.[6] [7]
These bacteria are normal constituents of the fish gills and gastrointestinal tract. The bacteria contain an enzyme, histidine decarboxylase, which breaks down the amino acid histidine into histamine when the temperature of the flesh reaches above 40°F. The histidine decarboxylase can continue to function even when the bacteria are no longer viable. Many fish proteins contain histidine, but fish that are darker in color tend to contain more. Each excursion above 40°F allows histamine to be produced, and the final amount of histamine is compounded. Neither cooking, freezing nor canning will destroy the heat stable histamine.[8]
Scombroid poisoning should be considered as a differential diagnosis in patients with symptoms suggestive of an allergic/anaphylactic reaction. While the initial treatment of both these conditions is similar, an accurate diagnosis of scombroid poisoning, along with reporting cases of scombroid poisoning to the relevant food agency will lead to early source testing and identification of the affected batch of product, which, in turn, will prevent further occurrence of the condition and improve food safety.[9]
[1] Katugaha, S. B., Carter, A. C., Desai, S., & Soto, P. (2021). Severe scombroid poisoning and life-threatening hypotension. BMJ Case Reports CP, 14(4), e241507. https://pmc.ncbi.nlm.nih.gov/articles/PMC8076943/
[2] Centers for Disease Control (CDC). (2024). Traveler’s Health: Food Poisoning from Marine Toxins. https://wwwnc.cdc.gov/travel/yellowbook/2024/environmental-hazards-risks/food-poisoning-from-marine-toxins
[3] Cheong, T., Pothiawala, S., David, E. K., & Cooke, V. A. (2023). Scombroid poisoning: An anaphylaxis mimic. Singapore Medical Journal.
[4] Zhernov, Y. V., Simanduyev, M. Y., Zaostrovtseva, O. K., Semeniako, E. E., Kolykhalova, K. I., Fadeeva, I. A., … & Mitrokhin, O. V. (2023). Molecular mechanisms of scombroid food poisoning. International journal of molecular sciences, 24(1), 809. https://www.mdpi.com/1422-0067/24/1/809
[5] Katugaha, S. B., Carter, A. C., Desai, S., & Soto, P. (2021). Severe scombroid poisoning and life-threatening hypotension. BMJ Case Reports CP, 14(4), e241507. https://pmc.ncbi.nlm.nih.gov/articles/PMC8076943/
[6] Cheong, T., Pothiawala, S., David, E. K., & Cooke, V. A. (2023). Scombroid poisoning: An anaphylaxis mimic. Singapore Medical Journal.
[7] Zhernov, Y. V., Simanduyev, M. Y., Zaostrovtseva, O. K., Semeniako, E. E., Kolykhalova, K. I., Fadeeva, I. A., … & Mitrokhin, O. V. (2023). Molecular mechanisms of scombroid food poisoning. International journal of molecular sciences, 24(1), 809. https://www.mdpi.com/1422-0067/24/1/809
[8] Katugaha, S. B., Carter, A. C., Desai, S., & Soto, P. (2021). Severe scombroid poisoning and life-threatening hypotension. BMJ Case Reports CP, 14(4), e241507. https://pmc.ncbi.nlm.nih.gov/articles/PMC8076943/
[9] Cheong, T., Pothiawala, S., David, E. K., & Cooke, V. A. (2023). Scombroid poisoning: An anaphylaxis mimic. Singapore Medical Journal.