Health and education officials in Hamamatsu, Shizuoka Prefecture, said Thursday that 905 students and 41 teachers and staff at 14 elementary schools suffered food poisoning on Wednesday and Thursday.
The affected people showed symptoms of food poisoning, said the local education board.
"Most of them developed such symptoms Wednesday night. They had eaten school lunch but any causal relation with the symptoms have yet to be confirmed," said Seiko Terada, director of health at the board.
"We have detected norovirus in 11 stool samples taken from some of the affected pupils," Hamamatsu city health official Toshihiko Furuta told a news conference late Thursday.
Twelve of the 14 affected schools were closed Thursday and will remain shut until at least the end of Friday.
According to the board of education, school lunches served this week might have been the source of the epidemic. Lunches are made at each school and health officials are checking to see if there were any ingredients sourced from the same supplier.© Japan Today/AFP