Nelson-Marlborough's Medical Officer of Health says there have been 20 confirmed cases of staff with Norovirus in hospitals in the regions since 2 July.
Ed Kiddle says people in Marlborough need to be aware that it is not just a hospital problem, and the virus will probably be the most common cause of diarrhoea and vomiting in the community.
He says Norovirus is very infectious, with an incubation period of 12 to 48 hours after contact.
Dr Kiddle says anyone that develops symptoms should not return to work until 48 hours after their last episode of diarrhoea or vomiting, as people are still infectious with Norovirus until 48 hours after their symptoms stop.
