A measles outbreak in the South Island is believed to have originated Australia.

Five people, from Nelson, Queenstown, Wanaka, and two from Christchurch, have contracted the disease after being exposed at Queenstown airport on March 21st or 22nd.

Canterbury Medical Officer of Health Dr Ramon Pink says they have traced the strain of the disease.

"This strain we know has been circulating across Tasman in Australia, and this strain has actually been transmitted into Australia in a traveller from Malaysia."

Dr Pink says the infected person may not have even realised they were sick.

He says even though they haven't identified who brought the disease in, they know where it's from.

"Identifying that strain shows that the likely source has been a traveller who was unaware that they were infectious who has come into New Zealand from Australia and has transmitted it to the cases that we've identified."

Dr Pink says they want to get a couple of key messages across.

"Getting vaccinated and calling ahead to your GP or ED so if you are unwell, you are not exposing other people unnecessarily."

READ MORE: Five cases confirmed as measles outbreak spreads across the South Island