Ten Rangitoto College pupils have tonight tested positive for influenza with health officials saying they consider it "likely" they have swine flu.
Swine flu is believed to have killed more than 80 people in Mexico and over 1300 are sick as a result of catching the virus which has also hit parts of the United States.
Health officials said tonight there were also three other high schools at risk with pupils from Northcote College having recently returned from Mexico, while Pinehurst and Westlake Girls High also had pupils in the United States and South America.
Health Minister Tony Ryall said most of the flu-affected pupils from Rangitoto College were on the "road to recovery", but other pupils had since come down with flu-like symptoms. Twenty-two pupils and three teachers were on the trip with 14 showing flu-like symptoms.
The affected pupils were being kept in isolation at home along with their family members.