The Department of Health and Human Services confirmed on Thursday it was contacting all sites in Ballarat and Melbourne where the adult had visited while infectious.

It’s believed the patient came into contact with another person carrying the infection on a Jetstar flight from the Balinese capital of Denpasar to Melbourne on September 28.

Measles is one of the most contagious airborne diseases in the world.

It has an incubation period of seven to 18 days, so anyone exposed to this new case in Ballarat may not develop symptoms until November 3. 

A spokesman for the Department of Health and Human Services told The Courier that measles can cause serious illness, particularly in very young children.

“The illness usually begins with common cold symptoms such as runny nose, red eyes and a cough, followed by fever and rash,” he said.

“The characteristic measles rash usually begins 3-7 days after the first symptoms, generally starting on the face and then spreading to the rest of the body. 

“Anyone developing symptoms is advised to ring ahead to their GP or hospital first and tell them that they have fever and a rash so that appropriate steps can be taken to avoid contact with other patients.” 

Most cases of measles in Victoria have been linked to international travel, with the disease more prevalent in many overseas countries, especially in Bali.

It comes after two people with measles attended Federation University on September 8, sparking a public health warning.

But that incident was not linked to this week’s new case.

The measles vaccine is recommended for babies at 12 months and again at 18 months.

“It is important to continue immunising children because of the risk that infection can be brought in by travellers arriving from overseas,” the spokesman said.

“Anyone who is unvaccinated is at risk of contracting measles.”