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  6. Scombrotoxin Poisoning and Decomposition
  1. Seafood Guidance Documents & Regulatory Information

Scombrotoxin Poisoning and Decomposition

An Advisory Note

This note is intended to assist the seafood industry and health professionals in addressing a unique form of food poisoning caused by consumption of certain marine fish species that have experienced partial bacterial spoilage. Scombroid poisoning is not usually a severe or long-term illness, and prevention is not difficult; yet occurrence continues about the world. The principal concern is for fresh fish, but the intoxication can result from consumption of certain frozen, cooked, cured or canned fish products.

What is scombroid poisoning?

Scombroid poisoning is a type of food intoxication caused by the consumption of scombroid and scombroid-like marine fish species that have begun to spoil with the growth of particular types of food bacteria. Fish most commonly involved are members of the Scombridae family (tunas and mackerels), and a few non-scombroid relatives (bluefish, dolphin or mahi-mahi, and amberjacks). A few additional species have been implicated, but they are of less concern relative to popular fish consumption. The suspect toxin is an elevated level of histamine generated by bacterial degradation of substances in the muscle protein. This natural spoilage process is thought to release additional by-products which potentiate the toxic effect. The potential toxins are not destroyed by freezing, cooking, smoking, curing or canning.

Where does scombroid poisoning occur?

Scombroid poisoning occurs wherever the particular marine fish species are eaten. Annual reported occurrence in the United States through the last two decades has been somewhat consistent despite the increasingly popularity of fish, particularly tuna fish. Knowledge of the causative factors and controls have directed effective industry and regulatory responses to assure proper handling and monitoring for the species of concern. In annual reports scombroid poisonings still rank among the top four most often reported seafoodborne illnesses. No doubt consumer mishandling in recreational and home settings can contribute to the incidence, and food service establishments must be better advised in product selection and handling.

How can one identify scombroid poisoning?

Confirmation for scombroid poisoning is a simple histamine analysis of the suspect fish. A common, routine fluorometric procedure can determine milligrams (mg) of histamine per 100 grams (g) of edible fish. Histamine concentrations near or above 100mg/100g are typically noted in actual illnesses. Regulatory guidelines have not been established for all the various fishes of concern, but 50mg/100g is inferred from the U.S. FDA's poisonous action level for tuna.

Symptoms of scombroid poisoning can become evident within minutes to 2 hours following consumption. This rapid onset is one reason scombroid poisoning may be reported more often than many other food poisonings which react much slower. Initial signs suggest an allergic response with facial flushing and sweating, burning-peppery taste sensations about the mouth and throat, dizziness, nausea and headache. These initial symptoms can advance to facial rash, hives, edema, short term diarrhea and abdominal cramps. Severe cases may blur vision, and cause respiratory stress and swelling of the tongue. Symptoms usually last for approximately 4 to 6 hours and rarely exceed one to two days.

Symptoms for scombroid poisoning can be easily confused with an allergy or other form of food poisoning, and vice versa. For example, some symptoms for scombroid poisoning are similar to ciguatera, another form of marine fish poisoning. Distinguishing these illnesses can be complicated, particularly about warm water regions.

What should one do if they suspect scombroid poisoning?

  • Consult a physician, explaining your concerns, types and amount of food eaten, and when the symptoms began.  
  • Try to obtain portions of the meal, particularly the suspect fish. These portions must be carefully handled, packaged and frozen to prevent any deterioration.  
  • Try to verify the species and size of suspect fish, and how it was cooked and handled prior to cooking. Inquire where the fish came from. Knowledge of species, source and prior handling could implicate other forms of food poisoning. Note the method or source used to verify the species, realizing local vernaculars and menu nomenclature can be misleading. - Consult with other professional in public health, food safety regulation or academic research that can better advise your physician. Many physicians are not familiar with scombroid poisoning.

What should one do to avoid scombroid poisoning?

Remember potential scombrotoxic fish belong to a particular group of species that have been allowed to initially spoil. These species should always receive special care in handling, washing, and proper icing, refrigeration or immediate freezing to prevent bacterial growth and spoilage. Studies have demonstrated toxic histamine levels can be generated within less than 6 to 12 hours exposure without ice or refrigeration. This problem is of particular concern immediately after catch aboard a commercial or recreational boat. Likewise, the recreational catch lying on a warm dock or beach is prone to histamine production in certain species. The adverse consequence is not severe, but discomforting and alarming enough to warrant a little extra care. Prevention is simple and preferable to treatment which is similar as used for allergic reactions. Common advice from physicians includes treatments with antihistamines.

Additional References

Lange, W.R. 1988.  Scombroid poisoning.  American Family
Physician 37 (4) 163-168.

Ragelis, E.P. (Ed.)  1984.  Seafood Toxins [Scombroid Fish
Poisoning - Chaps. 35 thru 37|.  American Chemist Society,
Washington, DC 460 pp.

Taylor, S.L., 1988.  Marine toxins of microbial origin.  Food
Technology. 53(3) 964-98.

Additional Advice

Dept. of Agriculture and Consumer Affairs Food Laboratory
3125 Conner Blvd.
Tallahassee, FL 32301
(904) 488-0670

Dept. Health and Rehabilitative Services
Disease Control Epidemiology Section
1317 Winewood Blvd., Bldg. 2, Room 275
Tallahassee, FL 32399-0700
(904) 488-2905

Dept. Natural Resources
Bureau Marine Science and Tech.
100 8th Avenue, S.E.
St. Petersburg, FL 33701
(813) 896-8626

University of Florida
Seafood Technology
Dept. Food Science and Human Nutrition
Gainesville, FL 32611
(904) 392-1991 or 2558

*Produced December, 1989, by Dr. W. Steven Otwell, Seafood specialist, Food Science and Human Nutrition Dept., University of Florida, IFAS Cooperative Extension Service and Florida Sea Grant Program with support through the U.S. Department of Agriculture's Cooperative Extension Service.

The State University System of Florida Sea Grant Program is supported by award of the Office of Sea Grant, National Oceanic and Atmospheric Administration, U.S. Department of Commerce contract number 04-7-158-44046, under provisions of the National Sea Grant College and Programs Act of 1966. This information is published in cooperation with the Florida Cooperative Extension Service, John T. Woeste, Dean, in conducting Cooperative Extension work in Agriculture, Home Economics, and Marine Sciences, State of Florida, U.S. Department of Agriculture, U.S. Department of Commerce, and Boards of Country commissioners cooperating. Printed and distributed in furtherance of the Acts of May 8 and June 14, 1914.

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