Scombroid poisoning outbreak sickens dozens at Japan school, linked to swordfish
Officials with Nagano Prefecture, located at the center of Japan’s Honshu island, are reporting an outbreak of scombroid fish poisoning affecting dozens at three elementary and junior high schools in Hakuba Village.
On December 9, officials say at least 46 children, students, and teachers that ate school lunches were affected. Swordfish is implicated in the scombroid outbreak.
To prevent a recurrence, the prefecture has suspended operations at the school lunch center that provided the food until the 10th. It has said it will review its cooking processes and safety management, and will instruct staff to defrost the food in the refrigerator or under running water rather than at room temperature.
According to the FDA, scombroid poisoning is a type of food intoxication caused by the consumption of scombroid and scombroid-like marine fish species that have begun to spoil with the growth of particular types of food bacteria. Fish most commonly involved are members of the Scombridae family (tunas and mackerels), and a few non-scombroid relatives (bluefish, dolphin or mahi-mahi, and amberjacks). A few additional species have been implicated, but they are of less concern relative to popular fish consumption.
The suspect toxin is an elevated level of histamine generated by bacterial degradation of substances in the muscle protein. This natural spoilage process is thought to release additional by-products which potentiate the toxic effect. The potential toxins are not destroyed by freezing, cooking, smoking, curing or canning.
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Symptoms of scombroid poisoning can become evident within minutes to 2 hours following consumption. This rapid onset is one reason scombroid poisoning may be reported more often than many other food poisonings which react much slower. Initial signs suggest an allergic response with facial flushing and sweating, burning-peppery taste sensations about the mouth and throat, dizziness, nausea and headache. These initial symptoms can advance to facial rash, hives, edema, short term diarrhea and abdominal cramps. Severe cases may blur vision, and cause respiratory stress and swelling of the tongue. Symptoms usually last for approximately 4 to 6 hours and rarely exceed one to two days.
Remember potential scombrotoxic fish belong to a particular group of species that have been allowed to initially spoil. These species should always receive special care in handling, washing, and proper icing, refrigeration or immediate freezing to prevent bacterial growth and spoilage. Studies have demonstrated toxic histamine levels can be generated within less than 6 to 12 hours exposure without ice or refrigeration. This problem is of particular concern immediately after catch aboard a commercial or recreational boat. Likewise, the recreational catch lying on a warm dock or beach is prone to histamine production in certain species.