There has been a fourth case of measles in Auckland.
The Auckland Regional Public Health Service said the new case was an 18-year-old university student.
It is suspected the student acquired the illness overseas.
Authorities are now working with the University of Auckland to track down students and staff who have been in classes with the student.
The contagious student attended a lecture and a tutorial for COMLAW 101 on Monday 11 March, a lecture and tutorial for ECON 151 on Tuesday 12 March, and a BUSINESS 101 lecture on Thursday 14 March.
Medical Officer of Health William Rainger said the university is emailing information to those registered on these courses and the teaching staff to ask they check their immunity and watch out for symptoms.
"If any student or staff member is showing signs of measles such as a fever, runny nose or cough, or sore red eyes, or a rash that appears on the face and then moves down the body, we are asking them to please call their GP or after hours medical clinic for advice," he said.
Health authorities were also checking the student's household and other contacts to assess immunity, discuss quarantine and monitor any symptoms.
The case is not linked to two other cases notified last Tuesday, or a case in late February.