Canterbury Medical Officer of Health Dr Alistair Humphrey said measles was highly infectious.
"The measles virus spreads easily from person to person through the air, via breathing, coughing and sneezing. It starts with fever, runny nose, cough, red eyes and sore throat. This is followed by a rash that spreads over the body. Complications include pneumonia, inflammation of the brain and damage to the eyes."
It could take up to three weeks for symptoms to appear, and people who were in the Emergency Department after 1pm on Sunday 28 January were being urged to phone their own family doctor or general practice team if they were concerned.
If it's after-hours a nurse would answer the call and advise what to do and where to go if you need to be seen.
"Measles cannot be treated once you get it so the only way to protect yourself is to be fully vaccinated," Humphrey said. "People are only considered immune if they have received two doses of MMR vaccine and/or have had a measles illness previously and/or were born before 1969."