A dozen pupils at a West Auckland primary school where a child has fallen ill with mumps have been forced to stay home until they can prove they are immunised.
As health authorities grapple with the worst outbreak in a decade the number of new mumps cases across Auckland and Waikato keeps rising.
There are now nearly 168 cases confirmed cases across the two regions.
The contagious disease has hit people aged between 10 and 29, with half of those falling ill are school children. Several teens have been hospitalised with complications.
Thirty Auckland schools have been affected, and non-immunised students have to stay home for weeks at a time.
Yesterday 12 pupils at Lincoln Heights School were officially excluded until a health professional could confirm their immunity.
Principal Debbie Waikato said just one pupil had mumps but to stop it spreading further those identified as most at risk were barred from class.
The school was operating as normal today, including swimming lessons, technology and a sailing trip on the Waitemata on the day of the America's Cup parade.
The latest figures show 153 cases in Auckland, up from 138 cases on Monday, and 15 cases in Waikato.
Auckland Regional Public Health Service clinical director Dr Julia Peters said it was now considered to be a major outbreak and urged parents to check with their doctor to ensure their families' measles, mumps and rubella (MMR) vaccinations were up to date.
"The majority of cases are aged 10 to 29 years as this age group has had lower than average immunisation rates," said Peters.
About 80% of the current cases were not fully vaccinated.
The public health service said the primary sign of mumps was swollen salivary glands but other symptoms included headache, muscle aches, fever, pain in the jaw and fatigue.
