A NSW man, who caught a train from the Brisbane International Airport to South Brisbane, 8am on Saturday, was diagnosed with a contagious measles virus.
Now Queensland's Health authorities are now tracking down those people who may have been exposed to the virus on the Brisbane train.
Christine Selvey, senior director of the Queensland's Communicable Diseases Branch, said that the measles symptoms develop usually about 10 days upon exposure.
It includes fever, runny nose, moist cough, fatigue, sore eyes and a blotchy red rash.
Measles easily spread in tiny droplets through coughing.
Dr Selvey said that the virus could last up to two hours in the environment and that vaccination is the most immediate cure to prevent the disease.
People who may have traveled with the man should contact 13 HEALTH now.