A child with measles has been taken to hospital and five other cases of the virus have been confirmed after infected passengers arrived in Auckland on a flight from Brisbane two weeks ago.
More than 100 further cases are being investigated by the Auckland Regional Public Health Service.
The service was told last week of four infected passengers on Emirates Flight EK434, which arrived in Auckland at 5.30pm on January 11.
Medical Officer of Health Dr Richard Hoskins said now two further cases of the highly contagious virus had been confirmed and others were likely.
All the confirmed cases had come from a large family group flying together on the flight from Brisbane.
"All of the confirmed cases are young people aged 5 through to 16 years old, and one of those was hospitalised because it was so severe.
"They have almost certainly caught measles on the plane from the infectious cases. Measles is very easily transmitted from one person to another through the air, for example, while walking past the passengers with measles, or while waiting in the airport gate lounge."
Due to measles' highly contagious nature, he said, anyone who had been in contact with the infected people might now be infected themselves.
The Public Health Service is trying to contact anyone who has come into contact with the people who have the confirmed cases of measles.
"It is extremely contagious. If you even breathe in the air of someone who has it and exhales near you, you could catch it," Dr Hoskins said.
Once diagnosed the decision would be made on what the treatment options were, including possible isolation.
Dr Hoskins said measles was very serious and 30 per cent of people who caught it developed complications.
The only way to be immune was to keep up to date with immunisations or to have had measles before, he said.
He said if anyone caught the disease from the flight they would have already started showing the symptoms of high fever, a runny nose, red eyes, a cough, spots in the mouth or a rash.
Anyone with those symptoms should see their doctor or call Healthline on 0800 611 116 as soon as possible.