Some Dunedin schools appear to have been struck by gastroenteritis, with one primary school reporting up to 30 pupils recently caught the bug.
Macandrew Bay School principal Bernadette Newlands said she had heard other schools had been affected by gastroenteritis in the last few weeks.
It hit her school the weekend before last.
The illness, which produced diarrhoea and vomiting, struck one group of children.
''They seemed to be going down with it like flies.''
On the Monday there were ''an awful lot of absences''.
While the illness had now mostly passed, up to 30 pupils were off school at its height.
''Last week was the awful week,. It [the illness] seemed to be quite fast-moving.''
Ms Newlands said her ''guesstimate'' was 80 people in the Macandrew Bay community had the illness, including brothers, sisters and parents of pupils.
The school asked Public Health South for advice on how to manage the illness.
The response included an upgraded cleaning regime while children were sick, and advice to families not to send children back to school too early after having the illness, instead leaving it 48 hours after the last ''episode''.
