AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Scombroid fish poisoning (scombrotoxism, scombroid ichthyotoxicosis) is a food-related illness typically associated with the consumption of fish. Originally, the illness was associated with Scombroidea fish (eg, large dark meat marine tuna, albacore, mackerel); however, the Centers for Disease Control and Prevention (CDC) have identified the largest vector to be nonscombroid fish, such as mahi-mahi and amberjack. A case report documents a large outbreak related to escolar (rudderfish, oilfish) consumption, a species whose high waxy ester content can cause some gastrointestinal symptoms (keriorrhoea) that may overlap with those caused by scombroid poisoning.¹ Epidemiologic data from the CDC suggest that scombroid poisoning is the principal chemical agent type of food-borne disease found in the United States; the second most common is ciguatera poisoning.

Pathophysiology

Most of the published literature suggests that symptoms are related to the ingestion of biogenic amines, especially histamine. The histamine is produced via bacterial decarboxylation of histidine and is normally present at levels less than 0.1 mg per 100 g of fish. In contrast, samples of fish that produce poisoning contain histamine levels of at least 20-50 mg per 100 g of fish. Serum histamine levels and urinary histamine excretion are elevated in humans with acute illness. Antihistamines (H1- and H2-blockers) have been used with good efficacy and safety to abate or abolish the symptoms.

Frequency

United States

Scombroid poisoning is relatively uncommon (although likely highly underreported), making up 5% of food-borne disease outbreaks reported to the CDC. The American Association of Poison Control Centers does not maintain specific data on scombroid poisoning, as noted in its 1998 annual toxic surveillance report.

International

Although scombroid poisoning is more common in nations with a warm water fishing industry, the illness is worldwide in scope. The most commonly implicated fish species are scombroid dark meat fish (eg, tuna, mackerel, skipjack, bonito, marlin) and nonscombroid species, such as mahi-mahi (dolphinfish), sardine, yellowtail, herring, and bluefish. Although rare, cases of whitefish scombrotoxism also have been reported.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

The illness is usually self-limited but may cause significant discomfort. The onset of symptoms is usually 10-30 minutes after ingestion of the implicated fish, which is said to have a characteristic peppery bitter taste. The symptoms are nonspecific and may include the following:

• Flushing
• Palpitations
• Headache
• Nausea
• Diarrhea
• Sense of anxiety of unease
• Prostration or loss of vision (rare)

Physical

• Diffuse, macular, blanching erythema (most common)
• Tachycardia
• Wheezing (generally only in histamine-sensitive asthmatics)
• Hypotension or hypertension

Causes

• The bacterial decarboxylation of histidine usually present in fish tissue requires time and moderate temperatures. Thus, the most common causes of clinical illness are the consumption of spoiled fish, consumption of caught fish that has been cooled and refrigerated inadequately, or consumption of frozen fish that has been allowed to sit at room air temperature for a prolonged time after thawing.  The most effective preventive measure is the maintenance of chilled temperatures (<40°F [<4.4°C]) from the time of catch until cooking or consumption.
• Generally, consumption of larger amounts of scombrotoxic fish produces more symptoms. Eating a portion of fish closer to the outside of a previously frozen mass of fish also causes more toxicity. Taste is a relatively insensitive measure of toxicity, since the lowest levels of histamine sufficient to cause symptoms cannot be tasted.
• Cooking does not inactivate the toxin.
• The degree of symptoms in individuals consuming the same meal may be quite variable. Magnitude of symptoms may be related to the following:
• • Individual differences in sensitivity to histamine (eg, symptoms may be markedly worse in persons taking isoniazid because of blockade of GI tract histaminase)
  • Size of the portion consumed
  • Whether the portion was from the same fish
  • How cold the fish was before cooking (ie, more thawing may have taken place at the surface, and a fish portion from this area may contain more histamine)

DIFFERENTIALS

Section 4 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Acute allergic reaction
Carcinoid syndrome
Chinese restaurant syndrome (monosodium glutamate reaction)
Mastocytosis
Niacinlike reaction
Disulfiram, metronidazole, sulfonylurea reactions
Zollinger-Ellison syndrome
Pheochromocytoma
Migraine or cluster headache
Keriorrhoea, an oily diarrhea related to ingestion of marine wax esters

WORKUP

Section 5 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Generally, the diagnosis is clinical; no laboratory tests are necessary.
• If the diagnosis requires confirmation, histamine levels can be measured in a piece of frozen suspect fish.

Other Tests

• In patients in whom palpitations are a predominant symptom, an ECG may be necessary.

TREATMENT

Section 6 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Prehospital Care

• Prehospital care is primarily supportive.
• Provide oxygen and monitor cardiac function as needed.
• Antihistamines and bronchodilators may be used as needed if advanced life support personnel are involved.

Emergency Department Care

If the patient only has minimal symptoms, reassurance and observation may be the only treatment necessary.

• If clinically necessary, obtain an ECG and institute intravenous access, oxygen, and cardiac monitoring.
• Serum histamine levels and urinary histamine excretion are elevated in persons with acute illness. Treat with antihistamines as needed; H1- and H2-blockers may be useful.
• Consider use of activated charcoal only if presentation is very early and a large amount of fish was ingested.
• Although bronchospasm is rare, use standard treatment if it occurs.
• Extremely rare reported cases of myocardial dysfunction, ischemia, or infarction related to scombroid poisoning exist; standard treatment for these complications, including pressors, should be used. One reported case documents successful treatment of a 36-year-old woman with severe myocardial dysfunction refractory to pressor support by using a biventricular assist device for 8 days.²

Consultations

Consult the regional poison control center or a local medical toxicologist (certified through the American Board of Medical Toxicology or the American Board of Emergency Medicine) for additional information and patient care recommendations.

MEDICATION

Section 7 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

If the patient is symptomatic enough to require treatment, antihistamines are used to counteract the excessive histamine-induced effects; H1- and H2-blockers may be useful. Epinephrine or other adrenergic agents are rarely necessary because the entire cascade of mediators released by a true allergic reaction is not found in scombroid poisoning. Blockade of histamine, the sole pharmacologic mediator of scombrotoxism symptoms, generally is the only treatment necessary. Adrenergic agents may be considered in the rare case of secondary bronchospasm or refractory hypotension associated with this type of poisoning.

Drug Category: Antihistamines

These agents directly counteract the symptom-causing histamine excess.

FOLLOW-UP

Section 8 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Inpatient Care

• Admission is required only under exceptional circumstances.

Further Outpatient Care

• The vast majority of patients may be discharged from the ED with oral histamine blockade treatment with H1- and H2-blockers for the next 3-5 days.

Deterrence/Prevention

• Avoid eating ocean fish that is partially spoiled or has been poorly refrigerated. Do not continue eating fish if an unusual peppery bitter taste is detected.

Prognosis

• The prognosis is generally excellent.

MISCELLANEOUS

Section 9 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to obtain appropriate history implicating the suspected toxic fish, thereby allowing others to become similarly afflicted

Special Concerns

• Remember public health issues. Notify the local board of health if the diagnosis is confirmed, especially if the source was public.

MULTIMEDIA

Section 10 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  An example of a typical scombroid rash, in this case from tuna. Image courtesy of Amanda Oakley, MBChB, FRACP.
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Media type:  Photo

Media file 2:  An example of a typical scombroid rash, in this case from tuna. Posterior view of the same patient as in Image 1. Image courtesy of Amanda Oakley, MBChB, FRACP.
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Media type:  Photo

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

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2. Grinda JM, Bellenfant F, Brivet FG, et al. Biventricular assist device for scombroid poisoning with refractory myocardial dysfunction: a bridge to recovery. Crit Care Med. Sep 2004;32(9):1957-9. [Medline].
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16. Morii, H, Kasama, K, Herrera-Espinoza, R. Cloning and Sequencing of the Histidine Decarboxylase Gene from Photobacterium phosphoreum and its Functional Expression in Escherichia coli. Journal of Food Protection. 2006;69:1768-1776.
17. Morrow JD, Margolies GR, Rowland J, Roberts LJ 2nd. Evidence that histamine is the causative toxin of scombroid-fish poisoning. N Engl J Med. Mar 14 1991;324(11):716-20. [Medline].
18. Perkins RA, Morgan SS. Poisoning, envenomation, and trauma from marine creatures. Am Fam Physician. Feb 15 2004;69(4):885-90. [Medline].
19. Predy G, Honish L, Hohn W, Jones S. Was it something she ate? Case report and discussion of scombroid poisoning. CMAJ. Mar 4 2003;168(5):587-8. [Medline]. [Full Text].
20. Sims JK. A theoretical discourse on the pharmacology of toxic marine ingestions. Ann Emerg Med. Sep 1987;16(9):1006-15. [Medline].
21. Smart DR. Scombroid poisoning. A report of seven cases involving the Western Australian salmon, Arripis truttaceus. Med J Aust. Dec 7-21 1992;157(11-12):748-51. [Medline].
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Article Last Updated: Dec 10, 2007