A second human case of the mosquito-born Murray Valley Encephalitis (MVE) virus has been detected in New South Wales.
The Murrumbidgee Local Health District confirmed a man in his 50s in the state's Riverina region was hospitalised after contracting the virus between January and February.
The infection is the second human case recorded in the state this mosquito season and comes on the back of three deaths from the virus in Victoria since February.
The man has since been discharged from hospital.
There is no vaccination or specific treatment for MVE, and in very few cases the virus can cause neurological illnesses.
Keira Glasgow, the director of NSW Health's One Health branch, urged people to avoid being bitten by potentially infected mosquitoes and to be vigilant for symptoms which are very rare, but serious.
Mild symptoms include fever, headache, nausea, and vomiting.
"Signs of severe infection include severe headache, neck stiffness, sensitivity to bright lights, drowsiness, confusion, seizures, and loss of consciousness," Ms Glasgow said.
Diagnosis 'difficult' for health system
The case follows recent detections in mosquitoes and sentinel chickens in western and southern NSW where surveillance is being carried out.
Ms Glasgow said the number of detections among the sentinel animals is "concerning", but there's been no MVE recorded in Hilltops, where the man lives.
The MLHD's director of public health Alison Nikitas said the man had exposure to the virus in other areas of southern NSW where the virus has been detected, going as far east as Shoalhaven.
She said the MLHD became aware of the man's case last week but only recently received a confirmed diagnosis.
"The diagnosis of MVE is actually quite difficult, and it takes a range of different testing methods," she said.
NSW Health said it has established an expert advisory panel with medical entomologists working on mosquito control and management in response.
Dr Nikitas said the mosquito season was coming to an end but people should not become complacent.
"MVE still has been found in those mosquito populations from late February into early March so there's still a potential risk," she said.
