Spoiled tuna can lead to severe symptoms ranging from D&V to flushing,
tachycardia and anaphylactic-like reactions including hypotension. The
scombroid fish also include mackerel and marlin. These fish cover great
distances and their muscles contain 2 dipetides in high concentrations
(carnosine and anserine) thought to be used in buffering. Histidine is a
component of each dipeptide and when bacterial spoilage occurs, histidine is
decarboxylated to histamine which causes the symptoms (Morrow et al, N Eng J
Med 1991; 324: 716-20).
Mast cells are not activated and the symptoms are due to ingested histamine
(hence the reaction is pseudoanaphylaxis). Although, in principle, severely
affected patients may recover with only antihistamine therapy, it would be a
brave emergency doctor who would withhold full anaphylactic treatment. Two
cases we were involved with received full support for suspected anaphylaxis,
including epinephrine.
Scombrotoxicity is one of the commonest fish poisonings world-wide and
likely to increase in the UK. Good storage is the key, but even cooking and
canning to not inactivate histamine. Common clues in the literature of
spoiled tuna include a peppery or metallic taste.
James Hooper
Head, Dept Clinical Biochemistry,
Clinical Director Laboratory Medicine &
Divisional Director, Clinical Support Services
Royal Brompton Hospital
Sydney St,LONDON SW3 6NP. UK
email: [log in to unmask]
phone: 44 (0)171 351 8414
fax: 44 (0)171 351 8416
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