A further five people in Auckland have been diagnosed with the measles.
Auckland medical officer of health Dr William Rainger said the total number of cases in the region had risen to nine but four of the five new cases were household contacts.
"There is one new case which isn't linked to an existing case, a woman in her 40s from Rodney," Rainger said.
He said the person was now in isolation, but she had been infectious since Monday March 18.
On the Monday, she visited the Countdown supermarket in Silverdale at 10am.
She then went to the Orewa Countdown at 11am before going to nearby Oliver's Cafe.
On Wednesday March 20, she visited the Four Square in Parakai at 4.30pm.
Anyone unvaccinated who was at one of these locations around these times or in the following hour may have been exposed to the virus.
They should watch out for a fever, especially with a runny nose, cough or red eyes. A rash starts on the face a few days later, moving down the body.
"We are tracing all household, work, social and other contacts of these cases to check their immunity, discuss quarantine and monitor the appearance of any symptoms, following standard public health procedures, Rainger said.
The Auckland Regional Public Health Service are advising people to consult with their general practice if they think they have been exposed to measles, but suggest phoning first.
The symptoms include fever, cough, runny nose, sore red eyes and white spots inside the mouth. After three to five days a rash appears on the face and then moves down the body.
For more information or advice on measles, please call Healthline on 0800 611 116 or see the Auckland Regional Public Health Service website.