A regional public health official in Auckland says an outbreak of measles there could spread throughout New Zealand.
There are now 104 confirmed cases of the illness, which is 10 more than a week ago.
Richard Hoskins says health agencies have seen 10 to 14 new cases each week for the past six weeks.
Dr Hoskins says it is not an epidemic yet, but there is a strong possibility that numbers will increase dramatically.
He is urging more people to get immunised, especially young people, as measles is very infectious.
Dr Hoskins says measles is usually a mild illness, but some people experience serious complications.
Waikato also has a spate of measles cases, with 12 confirmed cases, up two on a week ago.
