We also find out where the measles has come from, who are the main people infected, and how easily it has spread.
One of the main sources of Bay of Plenty's measles outbreak is a medical waiting room.
Public health authority Toi Te Ora confirmed today the number of people with measles in the Bay of Plenty and Lakes districts has now reached 17.
Chief medical officer Dr Phil Shoemack said the increasing number of people with measles was concerning and it was essential people were immunised because the illness was so highly infectious.
"We know four or five cases most likely picked up their infection in a waiting room at one of the medical clinics. Unfortunately, one of our patients, who