About 300 children and others who ate school lunches at four elementary and junior high schools in Matsue fell ill on the 29th, and the city board of education says a health center investigation found the cause was histamine in grilled fish served with the meal. The board described the cases as a mass food poisoning outbreak.
Histamine is a compound that forms in fish when it spoils or is stored badly, and it is not destroyed by cooking. The board's announcement ties the illnesses to the fish itself rather than to handling at the schools.
The investigation was carried out by the public health center, which identified histamine as the cause. The board did not say in its announcement how the fish came to contain the compound or what checks it passed before reaching the schools.