Australians travelling overseas should check they have been vaccinated against measles regardless of their destination as health experts warn the highly contagious disease could take hold here.
The 84th case for the year was confirmed late on Monday after an unvaccinated international backpacker caught the disease in a Melbourne hostel.
The man in his 30s then travelled to several popular tourist locations in Sydney, including the Opera House, before catching the XPT train to Brisbane and staying at a Highgate Hill hostel.
The nation recorded 103 cases in 2018 and only 81 for 2017.
NSW Health's Dr Jeremy McAnulty said the dramatic increase in cases in Australia was a serious concern.
"We are really worried it could take hold here," the health protection director told AAP.
The spate of cases has been caused by unvaccinated travellers bringing it to Australia and unknowingly spreading the disease, he said.
Even for Australians not travelling to countries already hit by a large outbreak, like the Philippines, there's a chance of exposure in airports and on planes.
"For example, people travelling to London and stopping off in Dubai are exposed to a mass of people from around the world," he said.
After being exposed to a person carrying measles it can take up to 10 days to see symptoms, while others can see a rash within just four days.
Despite not showing symptoms people can be infectious soon after exposure, Dr McAnulty said, adding the best prevention was immunisation.
Anyone born after 1965 who is unsure if they have had two doses of the vaccine can check the Australian Immunisation Register, which has records from 1996 onwards.
Otherwise, visit a GP for a free vaccination.
All people born in 1965 or earlier will already be immune while babies headed overseas can be given one measles shot from nine months old, instead of at 12 months old, as scheduled.
Health Minister Greg Hunt said 95 per cent of the community needed to be vaccinated to achieve herd immunity which helps prevent the spread of the disease.
He said 93.5 per cent of two-year-old children had received two doses of the vaccine.
"Immunisation saves lives. The measles vaccine is very effective at protecting lives," Mr Hunt said in a statement.
NSW Health has issued several measles warnings in the past week, including after two infants caught the disease in Sydney and two unvaccinated Australians brought the disease from Asia to the state's north coast.
Dr McAnulty said anyone concerned they might be infected should report it directly to a doctor rather than potentially infecting others in waiting rooms.
The World Health Organisation website reports that so far this year, the Philippines has reported 23,000 cases with 333 deaths -- already more than all of last year.
Australia, Cambodia, China, Hong Kong, New Zealand, the Republic of Korea, Singapore and Vietnam have all recorded measles cases this year.
WHO Western Pacific Regional Director Dr Takeshi Kasai said measles spreads like wildfire.
"It is the most contagious human disease, and it's very good at seeking out and spreading among even small groups of people who are not immune," Dr Kasai said.
Australian Associated Press