Western Australian health authorities are warning of a measles outbreak in Perth's southern suburbs, with five confirmed cases reported in the Rockingham area in the past week.

Key points: One of the five confirmed cases is an infant under the age of 12 months

One of the five confirmed cases is an infant under the age of 12 months WA's Department of Health is urging people who show symptoms to contact their GP

WA's Department of Health is urging people who show symptoms to contact their GP A new adult measles vaccine was released in March for people aged between 20-53 years

The five cases include a baby under 12 months old, who is too young to be vaccinated, and several people in their 40s.

The WA Health Department said measles had been all but eliminated from the state for about 20 years, however occasional cases and small outbreaks still occurred.

The department's Dr Paul Effler said it was "unprecedented" in his experience to have five measles cases in a weekend.

"Now, I don't think it will mean we'll continue to have five cases every week coming down in the future, but I think it is an indication we need to do more, that there is more work to be done in protecting our community from measles," he said.

Health authorities believe the outbreak started with a man from New Zealand, who has since returned there.

There have been more than 1,300 cases of measles in New Zealand recently, and the deaths of two foetuses in pregnant women were believed to be related to measles.

"This really stresses why other people need to step up and be vaccinated, because there are people too young to be vaccinated, people who have medical conditions that prevent them from being vaccinated, and for example, pregnant women who may not have had two doses are vulnerable," Dr Effler said.

People urged to check their vaccine records

Dr Effler said measles was a serious and highly contagious virus.

"Every measles case is treated as a public health emergency because of the risk of local spread," Dr Effler said.

Dr Effler said information had been provided to people who were potentially exposed to the most recent cases in Rockingham, but said it was difficult to identify and specifically warn people who were in public places.

He urged people to check their health records to see if they and their children had been vaccinated twice for the disease.

"So, I think at this point, rather than trying to focus on putting out spot fires it makes much more sense for everyone to check their record and get vaccinated with two doses if they haven't done so already in their life, if they're 53 years or younger," he said.

The measles virus survives less than two hours in the air or on objects and surfaces and is inactivated rapidly in the presence of sunlight or heat.

People with measles typically develop symptoms approximately 10 days after being exposed to the virus.

Early symptoms include fever, cough, runny nose and sore eyes, followed by a red blotchy rash three or four days later.

Children between the ages of 12 months and 18 months are urged to receive a measles vaccination, while a new adult vaccination was released earlier this year for people aged 20-53 years.