Health officials have issued a warning to passengers on a flight from Jakarta to Perth last Sunday, after one passenger was confirmed with infectious measles.
The WA Health Department said this afternoon that passengers on Garuda flight GA724 on December 15 may have been exposed to measles because the person would have been infectious with the disease.
Dr Paul Armstrong, director of communicable disease control, said measles was highly contagious in people who were not fully immunised.
"The local public health units are contacting passengers who were seated closest to the infected passenger and are most at risk. Passengers seated elsewhere on the plane may have been exposed to the virus and should also be alert for symptoms," he said.
"Passengers who develop these symptoms should seek medical attention, but it is important they phone ahead first to ensure they don't share the waiting area with other patients and risk infecting them."
Susceptible passengers who may have been exposed to measles on the flight could expect symptoms to appear any time from this weekend until about January 2.
The passenger also visited several sites in Perth while infectious on December 16, including Kings Park, the University of WA, Forrest Chase, Willetton and Nedlands. Although the risk of infection was lower, people who were in these areas on that day should also be alert for symptoms.
"Measles is highly infectious and is spread through coughing and sneezing, and symptoms can include fever, tiredness, runny nose, cough and sore red eyes which usually last for several days before a red, blotchy rash appears," Dr Armstrong said.
"Complications can range from an ear infection and diarrhoea to pneumonia or swelling of the brain."
People up to the age of 47 who had not received two doses of measles vaccine were particularly susceptible to measles but those born before 1966 were usually immune because they had measles during childhood.
Children should receive two doses of measles vaccine at 12 and 18 months of age.