Passengers who took a flight from Jakarta to Perth on the weekend may have been exposed to measles, WA Health has warned.
The warning to passengers on Garuda flight GA724 on Sunday comes after a passenger was confirmed to have been infectious with the disease.
Local health officials 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.
Director of Communicable Disease Control Paul Armstrong said passengers who developed 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," Dr Armstrong said.
Symptoms can include fever, tiredness, runny nose, coughing and sore red eyes, which usually last for several days before a red, blotchy rash appears.
"Complications can range from an ear infection and diarrhoea to pneumonia or swelling of the brain," Dr Armstrong said.
He said people aged up to 47 years who have not received two doses of measles vaccine were particularly susceptible to the disease, but people born before 1966 were usually immune because they had measles during childhood.
Susceptible passengers could expect symptoms to appear any time between December 22 and January 2.
The passenger also attended a number of sites in Perth while infectious on Monday, including Kings Park, University of WA, Forrest Chase, Willetton and Nedlands.
Although the risk of infection is lower, people who were in these areas on that day should also be alert for symptoms.
Dr Armstrong said children should receive two doses of measles vaccine at 12 and 18 months of age.
