Early childhood centres and primary schools are on alert after a measles outbreak in Auckland.
"Fifteen people in Auckland have measles, a highly infectious disease," Auckland Regional Public Health Service clinical director Dr Julia Peters says.
Dr Peters says eight of those are related to a flight that arrived in Auckland but the others have no obvious identifiable source of infection.
"It suggests measles is spreading in the wider community," she says.
Measles is a serious and highly infectious viral disease causing fever, cough, sore red eyes and rash. The disease is infectious even before symptoms appear, which include fever, coughing, a runny nose, loss of appetite, and conjunctivitis.
Small white spots may be seen inside the mouth, followed by a rash covering most of the body and lasting four to six days.
Schools are informing parents about the outbreak and parents should check for signs in their children.
Dr Peters says the best protection is immunisation.
The service is urging schools to keep immunisation registers current and encourage students to be vaccinated.
"At enrolment, parents fill out a form to let us know if their child has been immunised or not. But it's an individual choice," Wainui School principal Gillian Bray says.
"Parents will generally let us know if their child is sick. We'll receive emails from the Ministry of Health. And we'll update parents as we learn more or if it becomes more widespread."
Louise Rauner, owner of Red Beach early childhood centre Hannah's House, says all the centre's children have had their shots.
But some parents are against vaccinations. Erwin Alber of Warkworth says his child, now grown up, was unvaccinated and if he had children again he still would not consent to vaccination.
"Measles, mumps and rubella are normal childhood illnesses which everyone my age group went through as there were no such vaccines around when I was a kid."
He says children who get childhood illnesses develop strong, life-long immune systems.
However, Dr Peters says vaccinations are "safe and effective". The only way any country can prevent outbreaks of measles is for "90 percent of the population to have had two MMR – mumps, measles and rubella – vaccinations."