The number of people who have come down with measles in the Auckland region since an Emirates flight arrived from Brisbane in mid-January has now hit 18.
Last week's figure was 15, with another likely to be confirmed and five more under investigation, Auckland Regional Public Health Service (ARPHS) said.
One of the people confirmed was on another incoming flight, a Malaysian Airlines service from Kuala Lumpur which arrived on February 18.
ARPHS medical officer of health Sheryl Jury said efforts were being made to find the people on the Malaysian Airlines flight who were sitting around the measles sufferer, to check their immunity.
Any passengers were asked to contact the ARPHS healthline or phone their doctor.
Dr Jury said measles was a serious illness for which 10 percent of sufferers needed hospital treatment, and it was particularly important it did not spread at present.
"Given the current national emergency with the Christchurch earthquake, it is particularly important that measles does not gain a foothold," Dr Jury said.
"ARPHS' role is contacting all the exposed people, assessing whether they are susceptible to measles infection, and providing public health advice including the need for isolation and further immunisation.
"The only way to protect from measles and its complications is to be fully vaccinated. My plea would be for parents and families to check that their children's immunisations are up-to-date."
Symptoms included a fever, cough, a runny or blocked nose, sore, red eyes and white spots inside the mouth. After three to five days a rash appears on the head and moves down the body.
Other cases of measles relating to the flight have been reported in Wellington and Christchurch.
