The virus is spread through mosquito bites and was diagnosed in an older man from Lake Cargelligo, who is likely to have acquired the infection early in November.

NSW Health executive director Jeremy McAnulty said the detection of the virus in the Lachlan Shire is a timely reminder for locals and visitors to be vigilant and safeguard against mosquito bites this summer.

"Mosquitoes in NSW can carry a range of viruses, including Murray Valley encephalitis virus, Kunjin virus, Ross River virus, Barmah Forest virus, as well as JE virus," Dr McAnulty said on Thursday.

"Vaccine is only available for JE, so avoiding mosquito bites is the most important way of preventing these infections."

He said it was vital everyone takes action to prevent bites as the summer holidays approach and people look forward to spending time outdoors.

Dr McAnulty recommends applying repellent regularly to exposed skin, wearing covered footwear and clothing that is loose, long-sleeved and light-coloured when outside, staying indoors at dawn and dusk and mosquito-proofing homes.

Anyone older than two months who lives or routinely works in at-risk local government areas is eligible for a free vaccination if they are regularly outdoors for long periods or helping with the flood clean-up.

JE vaccination clinics are being planned by the Murrumbidgee Local Health District for Lake Cargelligo for January.

Supply of the JE vaccine continues to be limited in Australia but additional vaccines are expected to arrive early next year.

Australian Associated Press