Officials are warning north Canterbury residents to be vigilant with hygiene following four confirmed cases of norovirus.
Two adults and two children from three different families in Waiau have the gastro bug. All are isolated in their homes.
Civil Defence has closed the welfare centre and communal kitchen in Waiau, where some of the people who have the gastro bug have visited in the past few days.
Canterbury Medical Officer of Health Dr Alistair Humphrey says people need to wash their hands before handling food and boil water.
He says many people now have power and running water in the town and that should help reduce the spread of norovirus.