A massive norovirus outbreak amongst school children in Japan has been, according to health authorities, linked to three factory staff who handled bread as part of their jobs. Japan News reports that norovirus was detected in stool samples of the three staff members – signs of the virus were not founds in an additional 16 food handlers who also submitted samples.

The bakery is suspected to have been the cause of a mass food poisoning that affected many primary schools in the city, according to the Hamamatsu city government.
The city government announced Sunday that workers at Hofuku, a company that produced bread deemed to be the cause of the norovirus outbreak, were found to be infected with the virus.

Yoshinao Terada, chief of the city government’s living and health section, said at a press conference, “It is highly likely that persons with the virus took part in the production process leading to contamination of the bread.”

The company ordered the three workers to stay home from work and specialists began sterilizing the plant. 

Asymptomatic norovirus carriers have been linked to lots of outbreaks in the past.  It’s also possible that the individuals were ill, recovered, and still shedding viruses in their stool. My NoroCORE colleague Robert Atmar and colleagues reported in 2008 that noro could be recovered from folks infected with the virus for up to 56 days (with a median of 28 days) – long after symptoms subsided.

Regardless, there are some hygiene issues going on at Hofuku.