I have an 81 y/o male with a prior h/o seasonal rhinitis and a distant past history of shellfish allergy with tolerance to shellfish for 10-20 years, who developed sudden onset generalized pruritis, total body erythema and syncope 1 hour after eating tilapia which had been prepared by his wife. He had eaten the same fish 4 days prior, and the portion he had ingested prior to this episode had been sitting in the refrigerator for four days (it was leftover). My initial impression was that this was a case of Scombroid (althouth tilapia is not a toxin producing fish I wondered if it was contaminated by other fish). I am in search of a place where I can send the actual fish that he had ingested for histamine testing (they saved a sample which has now been in the freezer). I called the FDA and the local department of health with no luck. In addition I would welcome any comment regarding this theory. Thank you.


Thank you for your inquiry.

First of all, although I have seen Scombroidosis, I have never had the opportunity of saving a sample of fish and sending it for analysis. However, this is an excellent idea. Normally, the FDA would be the group responsible for measuring histamine. I have copied for you below the CDC report indicating that FDA laboratories have done this in the past. I would, therefore, first contact the CDC since the initial report of an adverse reaction to a food would normally be reported there. I have also copied the contact information for you below.

"Scombroid Fish Poisoning- New Mexico, 1987. MMWR CDC July 29, 1988 / 37(29); 451.
In July 1987, state and local public health officials in New Mexico investigated two cases of scombroid fish poisoning (histamine poisoning) in persons living in Albuquerque. The New Mexico Health and Environment Department was initially consulted by an Albuquerque physician regarding two patients, a husband and wife, who had become ill within 45 minutes after eating dinner. Their symptoms included nausea, vomiting, diarrhea, headache, fever, flushing, and rapid pulse rate. An investigation by the Albuquerque Environmental Health Department found that the couple had shared a meal of grilled mahi mahi, pasta, salad, water, and wine. Their dog had eaten some of the fish and had vomited; however, their daughter, who had eaten no fish, did not become ill. Both of the patients had been treated with Benadryl, activated charcoal, and ipecac in a hospital emergency room. Their symptoms resolved within 36 hours of onset of illness.

Samples of the remaining mahi mahi were sent to the Food and Drug Administration laboratory in Seattle. Histamine was detected in the samples at a ratio of 20 mg/100 g, a level sufficient to cause symptoms (1). Samples from a different shipment of fish were obtained from the store in Albuquerque where the mahi mahi was purchased. These samples yielded histamine levels of 3 mg/100 g of sample and were negative for ciguatera toxin."
Contact Information
Centers for Disease Control and Prevention
1600 Clifton Rd. Atlanta, GA 30333, USA

In case you “draw blanks,” I have also copied below an abstract written by Dr. J. M. Hungerford who, at least at the time the abstract appeared in 2010, was at the FDA. I think it would also be worthwhile for you to directly contact Dr. Hungerford since he has a particular interest in Scombroidosis. His contact information is listed in the abstract.

“Toxicon 2010 Aug 15; 56(2):231-43. doi: 10.1016/j.toxicon.2010.02.006. Epub 2010 Feb 10.
Scombroid poisoning: a review. Hungerford JM.
ATC, PRL-NW, USFDA, 22201 23rd Dr S.E. Bothell, WA 98021, United States.
Scombroid poisoning, also called histamine fish poisoning, is an allergy-like form of food poisoning that continues to be a major problem in seafood safety. The exact role of histamine in scombroid poisoning is not straightforward. Deviations from the expected dose-response have led to the advancement of various possible mechanisms of toxicity, none of them proven. Histamine action levels are used in regulation until more is known about the mechanism of scombroid poisoning. Scombroid poisoning and histamine are correlated but complicated. Victims of scombroid poisoning respond well to antihistamines, and chemical analyses of fish implicated in scombroid poisoning generally reveal elevated levels of histamine. Scombroid poisoning is unique among the seafood toxins since it results from product mishandling rather than contamination from other trophic levels. Inadequate cooling following harvest promotes bacterial histamine production, and can result in outbreaks of scombroid poisoning. Fish with high levels of free histidine, the enzyme substrate converted to histamine by bacterial histidine decarboxylase, are those most often implicated in scombroid poisoning. Laboratory methods and screening methods for detecting histamine are available in abundance, but need to be compared and validated to harmonize testing. Successful field testing, including dockside or on-board testing needed to augment HACCP efforts will have to integrate rapid and simplified detection methods with simplified and rapid sampling and extraction. Otherwise, time-consuming sample preparation reduces the impact of gains in detection speed on the overall analysis time.”

Finally, the Mayo Clinic Laboratory is one of several that measure histamine. Of course, the assay is designed for the measurement of histamine in human blood, but it might be worth contacting them as well to see if this assay could be performed on your fish sample. Their contact information can be easily acquired by simply “Googling” Mayo Clinic Laboratory.

You have asked for any comment, and I think that you are pursuing the proper path in trying to measure histamine in your saved sample. There are a couple of features which may point against a diagnosis of Scombroidosis, in favor of an anaphylactic event. It is unusual, although it can happen, for a person to go into shock with Scombroidosis. The patient would have had to ingest a relatively large amount of histamine to do so. Shock is far more common during an anaphylactic event. In addition, if this food contained very large amounts of histamine, and anyone else at the table ate it with him (e.g., his wife), they would have been expected to have had symptoms as well.

Finally, as you mentioned, tilapia would be an unusual fish to cause Scombroidosis, although I assume it could occur after the ingestion of tilapia as well. However, because of these features, I would, if you have not already done so, evaluate him for anaphylaxis with skin tests and serum-specific IgE, and also, of course, take a thorough history as to preceding drug ingestion, et cetera - looking for other causes. That is, I think that, although Scombroidosis is certainly a possibility, it appears to be at least equally likely, if not more so, that he experienced a true anaphylactic event.

Thank you again for your inquiry. Also, we would greatly appreciate a follow-up if you do find the etiology of this episode.

Phil Lieberman, M.D.

Ask A Question

Healthcare Professionals: If you can’t find what you are looking for, please send us your question.

Due to the number of questions submitted to Ask the Expert, we are experiencing a significant delay in responses at this time.

Ask now

AAAAI - American Academy of Allergy Asthma & Immunology