Four cases of measles have been reported to Auckland Regional Public Health Service in a ten day period, which says it's likely more cases will be diagnosed in the next few days.
Earlier this year an outbreak occurred in which 24 cases surfaced.
Medical Officer of Health Cathy Pikholz says the latest cases, reported in the 10 days from 20 April, occurred in various parts of the city.
She says immunisation is the only effective way to prevent outbreaks, but people should be aware of symptoms which include a red rash, sore eyes, a runny nose and a fever.
She says there's a period of 10 days during which someone with measles is infectious.