An outbreak of what health authorities believe is Salmonella has sickened at least 1,048 students, teachers, and staff members at nine schools in Iwamizawa, a city of about 90,000 on Japan’s northern island of Hokkaido.

Students began to have severe diarrhea and other symptoms of foodborne illness last Friday after eating  a Thursday lunch of miso soup with potatoes, green salad, and Japanese radish with minced chicken, rice and milk. The meal was prepared in central kitchen for about 3,000.

Thirteen students have been hospitalized, according to news reports.  The public broadcasting system NHK reported that Salmonella had been confirmed in five patient cases.

School meals in Japan are typically prepared in large central kitchens and then delivered to schools–an efficient way to feed students but also to cause widespread foodborne illness.  In 1996, an outbreak in Sakai City, Japan, sickened at least 9,441 and killed 12, most of them school children–the worst toll of any recorded outbreak of E. coli O157:H7.  The source was believed to be contaminated radish sprouts. 

Following that outbreak, schools in Japan are now required to keep samples of all meals served over the previous seven days.