Scombroid Food Poisoning - Causes

Causes

Unlike many types of food poisoning, this form is not brought about by ingestion of a bacterium or virus. Histidine exists naturally in many types of fish, and at temperatures above 16°C (60°F) on air contact it is converted to the biogenic amine histamine via the enzyme histidine decarboxylase produced by enteric bacteria including Morganella morganii (this is one reason why fish should be stored at low temperatures). Histamine is not destroyed by normal cooking temperatures, so even properly cooked fish can be affected. Histamine is a mediator of allergic reactions, so the symptoms produced are those one would expect to see in severe allergic responses.