Scombroid poisoning. A report of seven cases involving the Western Australian salmon, Arripis truttaceus.

OBJECTIVE: To present the clinical findings of scombroid poisoning due to ingestion of the Western Australian salmon, Arripis truttaceus, occurring in two separate outbreaks involving seven patients. Both outbreaks occurred in March and the fish had been caught in South Australian waters. CLINICAL FEATURES: Onset of symptoms in all patients occurred within half an hour of ingestion of the affected fish. The clinical syndrome included erythema and urticaria of the skin, facial flushing and sweating, palpitations, hot flushes of the body, headache, nausea, vomiting and dizziness. The fish implicated in one outbreak was noted to have a peppery taste. The diagnosis of scombroid poisoning was confirmed by the presence of the clinical syndrome, and by demonstration of high histamine levels in the cooked fish. INTERVENTION AND OUTCOME: Two patients had minor symptoms which had resolved before seeking medical advice. Another two patients had mild symptoms which disappeared after two hours of observation and required no specific treatment. Three patients had evidence of major toxicity which was successfully treated with parenterally administered promethazine. One of the three patients with major toxicity required overnight admission and repeated doses of promethazine to eradicate her symptoms. No patient had symptoms for longer than 12 hours. CONCLUSION: Scombroid poisoning is caused by ingestion of fish which has accumulated scombrotoxin during spoilage. The toxin is heat stable and has been identified as histamine. The clinical presentation closely resembles an acute allergic reaction. This similarity in symptoms may result in the diagnosis of scombroid poisoning being missed by clinicians. Patients with the symptom complex may be incorrectly informed that they are allergic to the fish species. Diagnosis is clinical and can be confirmed by analysis of the histamine content of the fish. Treatment is with antihistamines, however major toxicity may require the same aggressive management as acute anaphylaxis.