Warning after Perth measles diagnosis

West Australians have been warned of a measles threat after a Perth resident returned home from Vietnam and was diagnosed with the illness.

A measles warning has been issued in Western Australia after a passenger on an Air Asia flight was diagnosed with the illness.

The Perth resident returned home from Vietnam on January 16, visiting work places and public venues last week, the WA Health Department said on Wednesday.

People should remain vigilant for measles symptoms until February 6 if they are not immune to measles.

Places visited by the person include areas of the Perth CBD, South Perth, West Perth, Rockingham and Mandurah.