Because of this, they may not realise they have the disease until after others have been infected.
Children who had received two doses of measles-mumps-rubella (MMR) vaccinations were protected.
Drumm said the school had a communicable diseases policy in place for the protection of the health of its students and staff, and also to protect the privacy of affected students or staff members.
"The school has received a small number of emails from parents thanking us for letting them know about the notified case," Drumm said.
"A few have chosen to keep their child home if their child is not immunised."
As the school term ended tomorrow, the public health service had advised it would be safe for all un-immunised children to attend school from the start of the fourth term.
Medical Officer of Health Dr Michael Hale said parents had been advised to keep the sick child away from school and in isolation for five days after facial swelling had begun.
"We received notification of the positive test on Friday 16 September, advised the family immediately and advised the school on the Monday," Hale said.
In Auckland, there were currently two known cases of mumps, both of which were acquired overseas.
Mumps cases were rare in Auckland because of generally high levels of vaccination.
"We currently average about three cases a year, usually acquired overseas," Hale said.
"Cases of mumps among school students are always a concern because of the heightened risk of the disease spreading in schools.
"While the rate of immunisation in the total population is high, it is lowest among the 10 to 35 year age group."
This meant it could spread easily in high schools, where there were a higher number of vulnerable people grouped together, and mixing freely.
"We encourage people to check their vaccination records with their GPs and arrange to get free catch-up vaccinations if they need them."
