JE is a rare but serious illness spread by infected mosquitoes.
In some cases it can cause severe neurological illness with headache, confusion, convulsions and reduced consciousness.
A probable case of JE is being investigated in a man in his 60s, who was likely exposed to JE virus in the Riverina region in late December.
Murrumbidgee Local Health District said, adding to the need for caution is the detection of other mosquito-borne viruses in 2025.
NSW Health's routine surveillance detected Kunjin virus through a sentinel chicken blood sample at Cowra on November 20, while Horsham Rural City Council region in Victoria recently detected Japanese Encephalitis virus in mosquito samples, marking the first detection of the 2025/2026 season.
MLHD public health director Alison Nikitas said these early detections are concerning.
“Mosquito numbers will likely increase with warmer weather, and we remind everyone in NSW to protect themselves against mosquito bites, which can cause diseases such as Japanese Encephalitis and Murray Valley Encephalitis, and infection with Kunjin virus, Ross River virus and Barmah Forest virus,” she said.
NSW Health can also advise of a recent detection of JE virus in the Upper Lachlan Shire near Goulburn through a sentinel chicken blood sample in early January 2026, which indicates that JE virus is likely circulating in the area.
NSW Health uses routine sentinel chicken surveillance to provide early warnings about the presence of mosquito-borne viruses.
Murrumbidgee director public health Alison Nikitas said given the widespread area of these detections, anyone living or working in areas at high-risk for JE should take steps to protect themselves by avoiding mosquito bites and getting vaccinated.
“There is no specific treatment for JE so it is very important for people who live in or travel to these areas to be aware of the elevated risk,” Ms Nikitas said.
“Importantly, there is a safe, effective vaccine to protect against JE virus which is free to anyone who lives or routinely works in various inland regions as well as for people who work in some other high-risk occupations.”
The Japanese Encephalitis vaccine is available through general practitioners, Aboriginal health services and some pharmacists.
Eligible people should make appointments in advance, as providers may require several days' notice to order the vaccine.
No vaccination exists for Kunjin virus or other mosquito-borne diseases in Australia.
Prevention focuses on avoiding mosquito bites, particularly between dusk and dawn when mosquitoes are most active.
Recommended protection measures include applying DEET, picaridin or oil of lemon eucalyptus repellents to exposed skin, wearing light-coloured, loose-fitting long clothing, avoiding outdoor activities during peak mosquito times, using insect screens on windows and doors, and removing water-collecting items from around homes.
For more advice, go to www.health.nsw.gov.au/mosquitoes.
