AN Adelaide woman has contracted measles from a stranger in a rare transmission of the virus in Australia.

The woman’s case has been linked to that of an Adelaide man who picked up the highly infectious virus while travelling overseas earlier this year.

SA Health yesterday warned South Australians to be alert for symptoms of the disease, which can cause brain damage in severe cases.

It is understood the woman, 44, was in the same vicinity as the man, 23, at some stage during his infectious phase.

They are not believed to be known to each other.

Measles cases have been rare in Australia since the measles vaccine was introduced in 1966.

In SA, 87 per cent of kindergarten-aged children receive vaccinations to protect them against infectious diseases including whooping cough, measles, mumps, rubella, tetanus and diphtheria.

Almost all cases are unimmunised travellers bringing the disease from overseas. There were four in SA last year but none spread to a stranger.

SA Health chief medical officer Professor Paddy Phillips said the infectious phase lasted about two weeks and the disease could be spread by coughing and sneezing.

He said the airborne virus was highly contagious among those who were not fully immunised.

"The illness begins with fever, cough, runny nose, and sore eyes, followed by a rash which begins on the head and then spreads down the body," he said. "Complications of measles can be severe."

Anyone who was at any of the following locations around Adelaide at the listed times should watch for symptoms over the next two weeks, Prof Phillips said.

Tuesday, January 31: 10am-2pm, West Lakes Shopping Centre.

Wednesday, February 1: 10am-3pm, Cyprus Community Club, Welland.

Thursday, February 2: 9.30am-12pm, Uniting Care Wesley, Adelaide; 10am-4pm, Thebarton Neighbourhood House, Mile end; 12pm-3.30pm, Woodville Bowl.

Friday, February 3: 9.30am-5pm, Cheltenham Community Centre; 10.40am train from Cheltenham to the city; 11am-2pm, Jasper’s Coffee shop, Adelaide; 12.07 pm train to Cheltenham.

SA Health has alerted each business and GPs.