Victoria is again on measles alert after two new cases were confirmed on Saturday, taking to 34 the number of infections recorded in the state this year.
News of the additional infections comes a day after a young Victorian woman who had been in Geelong, central Melbourne and bayside suburbs before boarding a Jetstar flight to Brisbane was diagnosed with the highly contagious disease.
Her travel movements have also put Queensland health authorities on alert.
On Saturday, Victorian health authorities expressed concern that the latest outbreak could mean multiple undetected cases could already exist within the community, adding to the potential for a "significant outbreak".
Victoria's acting chief health officer Finn Romanes said there was no direct connection between the three cases. However he said the risk of the infection spreading in Geelong, the Surf Coast, and central, western and northern parts of Melbourne was something authorities were investigating.
The three cases confirmed since Wednesday all relate to people aged 18 to 30 who became infected in early to mid-June. None had recently travelled overseas, the usual route by which measles enters Australia.
"Because of this, our concern is that there was a person or persons who probably had travelled overseas and have since unknowingly passed on measles to these three people in the western suburbs and Barwon area," Dr Finn said. "There may be more."
Measles has an incubation period of up to 18 days. Symptoms include fever, sore throat, red eyes and coughing. The characteristic rash usually appears three to five days after the first symptoms appear.
Dr Finn said anyone not fully vaccinated for measles and displaying symptoms should call ahead when seeking medical care to avoid further spreading the disease.
He said because of the disease's incubation period, the number of cases could yet rise.
Those considered most at risk of catching measles are those who have not been vaccinated or those who have only had one of the required two-dose vaccine. People who were born after 1966 or have compromised immune systems due to treatment for conditions such as cancer are also vulnerable to infection.
According to the latest figures, 94 per cent of Victorian children aged up to five years are fully immunised against measles. But Dr Romanes urged parents of all children to ensure their immunisations were up-to-date.
There have been 34 measles cases in Victoria so far this year, compared with 27 cases for the same period last year according to the Health Department.
