The virus was detected in a man in his 50s from Hilltops Local Government Area (LGA). It is the first time MVE has been identified in this region.
The man was infected between late January and mid-February 2023, and was most likely exposed to the virus at home but had exposures across southern NSW, including as far east as the Shoalhaven. He was admitted to hospital but has now been discharged.
NSW’s first case of the mosquito season, announced in February, was identified in a man in his 60s, who was potentially exposed to infected mosquitoes in the Temora Shire, Edward River Shire or Murrumbidgee Council areas.
MVE has also recently been detected in border communities in Victoria.
Keira Glasgow, Director of NSW Health's One Health branch, said the latest case follows recent MVE detections in mosquitoes and sentinel chickens in western and southern NSW where surveillance is being carried out.
"There is no vaccination or specific treatment for Murray Valley encephalitis, so we urge the community to do everything they can to protect themselves against mosquito bites," Ms Glasgow said.
"The best way to avoid infection is to avoid being bitten by mosquitoes, which are most active between dusk and dawn. Avoiding mosquito bites will also protect against other mosquito-borne infections including Japanese encephalitis, Kunjin and Barmah Forest viruses.
"Only a small proportion of people infected with Murray Valley Encephalitis virus will have any symptoms, which include fever, headache, nausea, vomiting, loss of appetite, diarrhoea, and muscle aches.
"Signs of severe infection include severe headache, neck stiffness, sensitivity to bright lights, drowsiness, confusion, seizures, and loss of consciousness."
Ms Glasgow said the number of MVE detections in mosquitoes and sentinel chickens this season was concerning. In response, NSW Health has established an expert advisory panel on mosquito control and management with medical entomologists from across Australia.
"We are looking closely at the various approaches to mosquito control in different environments and in areas with different population densities to help inform our approach to mosquito control and management in NSW," Ms Glasgow said.
