Victoria's health department has confirmed its first case of Japanese encephalitis virus for the 2022-2023 mosquito season.
The case was identified in a man in his 20s living in the Campaspe Local Government Area, north of Bendigo, which experienced devastating floods during October.
The Victorian Department of Health said in a statement it was likely the man became infected in early November but had recovered from the illness.
No other cases had been identified since.
Japanese encephalitis is a rare but potentially serious or fatal infection of the brain that spreads through mosquito bites, although most people are asymptomatic or experience minor symptoms.
A health department spokesperson said recent weather events had been favourable for mosquito-breeding and there were high insect numbers across many parts of the state.
The spokesperson said there was ongoing concern about the transmission of Japanese encephalitis virus in inland riverine regions, extending up towards the Murray River.
They said that while most mosquito species were merely a nuisance, the types of mosquitoes known to spread disease were increasing in number, particularly as summer temperatures rose and floodwaters become more stagnant.
Vaccine supplies limited
While a vaccine against the virus is available for high-risk groups, supply remains limited in Australia.
The department spokesperson said that, along with other states, it was considering whether to change the eligibility for the vaccine — depending on supply and case numbers over the season.
They said Japanese encephalitis was yet to be detected in mosquitoes or animals in Victoria this season, and ongoing testing was underway to help identify high risk areas.
Advice to prevent bites
The department advised people to reduce exposure by avoiding getting bitten in the first place.
"Taking steps to minimise mosquito bites is extremely important and should be taken by all Victorians, no matter where you live," Victoria's deputy chief health officer Associate Professor Deborah Friedman said.
People exposed to mosquitoes, particularly those camping or spending time outdoors in riverine areas, were advised to wear long, loose-fitting clothes, and to use mosquito repellent containing picaridin or diethyltoluamide on all exposed skin.
Accommodation including tents should be fitted with mosquito nettings or screens, and stagnant water around dwellings should be removed.
People eligible for the vaccine were advised to speak to their GP or pharmacist.
More information can be found on the Victorian health department's website.
