Brisbane is on measles alert after an adult on the city's southside was diagnosed with the highly infectious disease.
Queensland Health says a large number of people have been potentially exposed after the person flew from the Philippines to Sydney via Qantas and then to Brisbane on January 21.
They were likely infectious during the flight and when they visited the IGA at Carina, on Brisbane's southside, later that day.
Metro South Hospital and Health Service public health physician Dr Brad McCall said all Brisbane people needed to be on alert for symptoms, particularly those who may have come into contact with the patient on the flight or at the IGA.
Measles symptoms usually appear 10 days after infection and include fever, cough, runny nose, a red spotty rash and sore eyes a few days later.