Waikato health authorities have confirmed an extra two cases of measles in the past two days.
A three-month-long outbreak of measles in Auckland is thought to have spread to Waikato.
It had 10 confirmed cases on Monday and was analysing a further five cases.
A Waikato medical officer of health, Anita Bell, says there are now 12 confirmed and a further three suspected cases.
Dr Bell says one of the confirmed cases is a secondary case and Waikato regional public health officials are expecting more such cases.
A secondary case occurs when a person who has not been immunised catches measles from an earlier case before that person knew they had the disease, she says.
