A second case of Japanese encephalitis (JE) has been confirmed in northern Victoria, with health officials warning of widespread virus detection along the Murray River from Mildura to Moira.
“The resident was likely exposed in the Riverina region of New South Wales along the Murray River,” said Victoria’s deputy chief health officer Christian McGrath, who confirmed the diagnosis occurred in February.
This follows December’s case involving a man from Katunga in northern Victoria who “remains quite unwell,” according to Dr. McGrath. The news comes just one week after a Sydney man died while vacationing in southern NSW – the state’s third death since JE was first detected there in 2022.
Virus Spreading Across Eastern Australia
Health authorities have found “widespread evidence” of JE across eastern Australia, with five human cases reported in NSW and Queensland this season.
“In Victoria we’ve found detections right along the Murray from the Moira Shire up to Mildura,” Dr. McGrath said. “We have mosquito surveillance programs in place and we also do detections in environmental water samples.”
JE has also been detected at piggeries across Victoria, NSW, and Queensland.
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“Pigs get infected like humans. We’re called dead end hosts for the virus,” explained Dr. McGrath. “The virus normally gets transmitted by water birds and therefore just spreads throughout geographical areas by birds. There’s no real way to control the spread of the virus in that respect.”
The virus wasn’t detected on mainland Australia until 2021-22 and was “probably brought with changing water bird migration patterns,” with Dr. McGrath noting that “lots of contributing factors for that, of which climate change might be part.”
Who’s at Risk?
JE can cause serious brain infections, though over 90% of infections produce no symptoms. Those most vulnerable include:
- Children under five years old
- Older adults
- People spending time outdoors near the Murray River
When symptoms do appear (typically 5-15 days after exposure), they can include fever, headache, vomiting, and in severe cases, seizures, weakness, movement disorders, and coma.
Prevention Measures
Victorian health officials urge residents and visitors to high-risk areas to:
- Use mosquito repellent containing picaridin or DEET
- Wear long, loose-fitting, light-colored clothing
- Ensure accommodation has proper mosquito screens
- Limit outdoor activity during dawn and dusk
- Remove stagnant water where mosquitoes breed

Vaccination Program Expands
A free vaccine is available for eligible people in 24 local government areas across Victoria. Dr. McGrath reported an uptick in vaccination since early 2025.
“Eligible people really is anyone over the age of two months [of age] who spends time outdoors, so that’s a lot of Victoria,” he said. “We encourage people to get the vaccine and to talk to their healthcare provider.”
The Victorian government now recommends vaccine boosters for some people every one to two years after their primary shot if they remain eligible.