Scombroid Poisoning

OVERVIEW

Scombroid poisoning occurs after the ingestion of fish that have been stored or processed inadequately, leading to high histamine levels in the body. It is is one of the most common causes of morbidity associated with fish intake.

The term “scromboidism” derives from the Scombridae fish family, that makes up 51 species, including mackerel, tuna, and bonito.

The amino acid, histainde, is found in fish cutis and intestines. Histidine is decarboxylated to histamine by primarily enteric gram-negative bacteria (e.g., Morganella morganii, Escherichia coli, Klebsiella species and Pseudomonas aeruginosa). When fish are incorrectly stored, more histamine is produced as a result of bacterial overgrowth. Histamine does not change the smell or appearance of the affected fish and his heat-stable, remaining present after cooking, freezing, canning or smoking.

CAUSE

• The most common cause is consuming fish from the Scombridae family
• Non-scombroid species such as herring, sardines, anchovies, and mahi-mahi have been implicated in the syndrome and occasionally the ingestion of cheese such as Swiss, Cheddar and Gouda
• Fish may be fresh, canned or smoked
• Improper refrigeration of the fish before and after cooking
• Outbreaks are most common in summer

CLINICAL FEATURES

• Symptoms begin within 10 to 90 minutes after ingestion
• Flushing, rash, urticaria (generally widespread erythema, usually lacking wheals), palpitations, headache, dizziness, sweating, and burning of the mouth and throat
• Gastrointestinal symptoms can include abdominal cramps, nausea, vomiting and diarrhoea
• Severe complications rarely occur: bronchospasm, respiratory distress and vasodilatory shock
• Rash lasts 2–5 hours
• Other symptoms usually disappear within 3–36 hours

Example clinical case

A 38 year old male presents to ED with an erythematous and widespread rash 30 minutes after eating sushi at a restaurant. He is light-headed and has vomited once. Below are 2 photographs and 1 video of his rash.

DIFFERENTIAL DIAGNOSIS

• Scombroid poisoning is frequently misdiagnosed
• Allergic reactions typically affect one person who has a history of specific allergy
• With scombroid poisoning, more than one person, often with no history of allergies, may be affected.

INVESTIGATIONS

• The diagnosis is generally clinical
• Can be confirmed by measurement of histamine in spoiled fish
• Diagnosis supported by plasma histamine level or histamine metabolites (e.g., n-methylhistamine) in patient’s urine

MANAGEMENT

• Most instances of scombroid poisoning are self-limited
• Specific therapies can include rapid-acting antihistamines (usually H1-receptor antagonists)
• Adrenaline and corticosteroids are generally not indicated
• Supportive care and monitoring

DISPOSITION

• Public health authorities should be notified to investigate the source and remove the product from distribution

References and Links

LITFL

• CCC – Seafood poisoning

Journals

• Stratta P, Badino G. Scombroid poisoning. CMAJ. 2012 Apr 3;184(6):674.
• Byard RW. Death by food. Forensic Sci Med Pathol. 2018 Sep;14(3):395-401.
• Eyer-Silva WA, Arteaga Hoyos VP, Nascimento L. Scombroid Fish Poisoning. Am J Trop Med Hyg. 2022 Mar 21;106(5):1300.