A confirmed case of measles has sparked a fresh health alert after a traveller returned to Australia from a popular holiday destination while unknowingly infectious.

The infected person was on board Jetstar flight JQ60 from Bali to Brisbane, Queensland, on Tuesday, August 19, landing at 5.40am, and moved through Brisbane Airport until 7.10am.

That evening, they shopped at Yamanto Aldi between 5.50pm and 6.40pm.

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On Saturday, August 23, the person visited Footes Pharmacy in Boonah and later presented at the Boonah Hospital emergency department.

Authorities said the risk has passed, but anyone who was at these locations at the listed times should be on high alert for symptoms of measles, which include:

• Fever
• Cough, runny nose, red or watery eyes
• A red, blotchy rash appearing days later

It is believed the infected traveller contracted measles while overseas.

The infection is spread by breathing in airborne droplets from the coughs or sneezes of infected individuals, and a third of people who catch the measles will experience a complication.

“Measles is highly contagious and spreads easily, especially through coughing and sneezing,” Dr Catherine Quagliotto from West Moreton Health said.

She warned even brief exposure can lead to infection, and stressed that vaccination remains the best protection.

Complications, such as ear infections, pneumonia, and diarrhoea, can all require hospitalisation, and about one in 1000 patients can develop encephalitis, which is an infection of the brain.

Symptoms can appear up to 18 days after exposure.

Authorities are urging anyone experiencing symptoms to call ahead before visiting a GP or hospital to avoid spreading the virus.