The measles outbreak is now suspected to have spread to Northland as the number of cases in Auckland and Waikato continues to climb.
A three-year-old child who attended day care while in the infectious period has been identified with suspected measles, Northland District Health Board (DHB) medical officer of health Dr Clair Mills said.
The child, who was recovering at home, may have contracted the virus while visiting Auckland, where the virus originated.
"We are working with the child care centre, parents and general practice in the Ruakaka area to contain the spread of this disease and are in the process of identifying contacts and offering immunisation."
People who had not been immunised who had been in contact with the child would be asked to stay isolated at home for 14 days, she said.