A measles alert has been issued in New South Wales after an infected traveller returned from Thailand and passed through Sydney International Airport before visiting a hospital emergency department, prompting health authorities to urge anyone at the affected locations to monitor themselves for symptoms.

NSW Health confirmed the case on 12 November, bringing the total number of measles infections recorded in the state this year to 58.

Where and when the exposure occurred

According to NSW Health, the infected individual arrived at Sydney International Airport aboard Thai Airways flight TG475 from Bangkok at approximately 9.10pm on Saturday 7 November. They moved through the arrivals terminal and baggage claim area, remaining there until around 11pm.

The following day, 8 November, the same person attended the emergency department at Canterbury Hospital on Canterbury Road in Campsie, between 3.35pm and 4.45pm.

Health authorities have confirmed that neither location poses an ongoing risk to the public, but anyone present at those sites during the listed times is advised to watch closely for symptoms over the coming days.

Symptoms to watch for and what to do

Measles symptoms typically begin with fever, a runny nose, sore eyes and a cough. Three to four days later, a red, blotchy rash usually appears on the head before spreading across the rest of the body.

Sydney Local Health District Public Health Unit Deputy Director Dr Isabel Hess noted that the incubation period makes vigilance particularly important.

"It can take up to 18 days for symptoms to appear after an exposure, so it's important for people who visited these locations to look out for symptoms for this period," Dr Hess said.

Anyone who develops symptoms and was present at the exposure locations during the listed times is urged to contact a doctor or health service, including an emergency department, but to call ahead first to avoid sitting in waiting rooms alongside other patients.

Pregnant women, people with weakened immune systems and infants who were at an exposure location within the past six days are strongly encouraged to contact their local Public Health Unit on 1300 066 055.

Why measles remains a serious threat

Measles is one of the most contagious infectious diseases known, spreading through the air when an infected person coughs or sneezes. Despite being vaccine-preventable, it can cause severe complications including pneumonia, encephalitis (swelling of the brain), permanent disability and immune system damage. In some cases it can be fatal.

Dr Hess said the current global situation adds urgency to the vaccination message.

"Anyone born after 1965 needs to ensure they have had two doses of measles vaccine," she said. "This is especially important before overseas travel, as measles outbreaks are occurring in several regions of the world at the moment."

The measles-mumps-rubella (MMR) vaccine is available free in NSW for anyone born after 1965 who has not yet received two doses, as well as for children at 12 months and 18 months of age.

Checking your vaccination status

Health officials are reminding the community to review their immunisation records ahead of any international travel. With measles activity reported across multiple global regions, travellers returning through major hubs such as Sydney Airport represent a real transmission risk if they are not fully vaccinated.

People who are unsure about their vaccination history are encouraged to speak with their GP or visit a local health service. Those who believe they may have been exposed at the listed locations and are in a high-risk category should contact the Public Health Unit directly rather than waiting for symptoms to appear.

NSW Health continues to monitor the situation and will update advice if additional exposure locations are identified.