A woman from Queenstown is the latest person to have contracted measles, bringing the total number of cases to six infected in the South Island.
The woman in her 20's is confirmed to have travelled on Air New Zealand while infected with the viral illness.
Four of the six people confirmed to have contracted measles travelled through Queenstown Airport last month.
The latest case is a woman in her 20s who travelled while infectious on Air NZ Flight NZ 5642 from Queenstown to Christchurch departing 8.20am on April 7 and Air NZ Flight NZ 5653 from Christchurch to Queenstown departing 3pm on April 9.
Anyone who travelled on either of these flights should check their immunisation status with their GP.
But, Canterbury DHB medical officer of health Ramon Pink says it's important people with symptoms don't visit GP rooms or after-hours clinics but phone first for advice, to limit further exposure to other people.
They will first develop a respiratory type of illness with dry cough, runny nose, temperature over 38.5C and feel very unwell.
The rash starts on day four to five of the illness usually on the face and moving down to the chest and arms.
People are considered immune if they have received two doses of measles, mumps, rubella vaccine, have had a measles illness previously, or were born before 1969.
The best way to protect yourself from measles is to have two MMR vaccinations.