At least seven Australians have been infected by a Bali measles outbreak.

Health authorities are now warning travellers to the Indonesian island to ensure they are vaccinated against the highly infectious disease before they leave.

The caution comes after five Victorians, who were not vaccinated, contracted measles in Indonesia in a five-week period.

Victoria’s acting chief health officer Michael Ackland said the health department had tracked three additional cases back to the five travellers since their return.

Queensland health authorities detected three cases of measles in the state’s southeast in October in males who had recently returned from Bali.

Queensland Health spokesman Craig Brown said two were confirmed infected in Bali.

Dr Ackland urged travellers to get vaccinated.

Two doses were recommended for travellers who had never been vaccinated while those travelling within a month could have one dose before departure and a second on return.

Dr Ackland said the measles illness usually began with common cold symptoms such as fever, sore throat, red eyes and a cough, followed three to seven days later by a rash.

People who develop symptoms should alert their GP or hospital to minimise infecting others, he said.

“Immunisation is the best protection against measles,” he said.