Measles is on the move throughout the country, with 12 of New Zealand's 20 district health boards reporting confirmed cases.
A surveillance report by ESR released on Tuesday shows the highly infectious viral illness has spread to most regions this year.
The Auckland region (Auckland, Waitematā and Counties Manukau), Waikato and Bay of Plenty DHBs have all had outbreaks of measles.
There have also been cases in Northland, Lakes (Rotorua), Midcentral (Palmerston North), Hutt Valley, Capital and Coast (Wellington), Canterbury and Southern DHB areas.
Testing by ESR found six genotypes (strains) of measles circulating in New Zealand, public health physician Dr Shirley Crawshaw said.
There have been 195 confirmed cases of measles across the country since January 1.
Auckland – particularly west Auckland – has been hit hardest, with 100 confirmed cases as of Monday.
ESR data show Counties Manukau DHB had the biggest spike in cases in the week to June 7, followed by Northland.
Of the 195 measles cases, the majority were aged 20-29 (50 cases), followed by those aged 10-19 (40 cases) and then 30-49-year-olds (35 cases).
Thirty-four cases were in children younger than 15-months, the age of eligibility for the first MMR (measles, mumps, rubella) vaccine.
The vast majority of people with measles were recorded as 'European or other' ethnicity; 115 cases.
'Pacific' people were the next most affected group, making up just 30 cases.
Measles is almost entirely preventable through two doses of the MMR vaccine.
Of the total cases, 119 were not vaccinated.
Eight were partially vaccinated (one of two doses), 11 were fully vaccinated and a further 57 were 'unknown'.