Japanese encephalitis is a rare but serious illness caused by the Japanese encephalitis virus (JEV). It is spread to humans by infected mosquitoes.
Japanese encephalitis fact sheet
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Frequently asked questions
While Culex species of mosquitoes are most likely to be carrying the virus in NSW, mosquitoes are hard to identify and may also carry other viruses such as Ross River, Barmah Forest and, rarely, the virus that causes Murray Valley encephalitis, so it is important to protect yourself against all mosquitos.
Before the 2021-2022 mosquito season, Japanese encephalitis virus had rarely been found in Australia with previous cases noted only in Northern Australia, Cape York and the Torres Strait.
It is not known how Japanese encephalitis virus came into mainland Australia, but the movement of infected mosquitoes or migratory water birds may have played a part in the virus' spread, combined with significant rain events.
Japanese encephalitis virus has been detected in pigs, mosquitoes and humans in Western, Northern and Southern NSW, as well as in Queensland, Victoria, the Northern Territory and South Australia.
Animals can be infected with the Japanese encephalitis virus, but they cannot transmit the virus to humans. It cannot be transmitted by touching or eating meat from an infected animal.
Not all mosquitoes in NSW carry the Japanese encephalitis virus, but some do carry JEV as well as other diseases such as Barmah Forest, Ross River and more rarely, the virus that causes Murray Valley encephalitis. The best thing you can do is take steps to prevent being bitten.
JEV has been detected across parts of NSW west of the Great Dividing Range during the current summer (mosquito season). In addition to animal and mosquito detections of JEV, there have been human cases reported who have acquired the disease in NSW during this period.
It is anticipated that there is JEV circulating in areas of NSW west of the Great Dividing Range which has not been detected in surveillance systems. All residents and travellers to the 55 LGAs identified as higher risk should presume that the risk may be present in their region and take measures to prevent mosquito bites.
NSW recommends people continue to avoid mosquito bites this summer: spray up (use repellent), cover up (wear long-sleeved shirts and long pants), screen up (cover windows and doors with insect screens) and clean up (remove any containers that hold water where mosquitoes may breed). Further information is available at Mosquito-borne diseases.
Cases of Japanese encephalitis in NSW1
| 2021 - 2022 |
13 (2) |
|
2022 - 2023 |
1 |
|
2023 - 2024 |
0 |
2024 - 2025
|
5 (2)2 |
|
|
- Includes cases of JEV from other jurisdictions who likely acquired their infection in NSW
- Confirmed and probable cases.
NSW Local Government Areas (LGAs) where human cases were likely exposed to JEV
Balranald, Berrigan, Carrathool, Dubbo, Federation, Goulburn Mulwaree, Griffith, Hilltops, Gunnedah, Lachlan, Lockhart, Moree Plains, Murray River, Tamworth, Temora, Tenterfield, Wentworth
Note: Where human cases may have been exposed in multiple LGAs, all LGAs are listed
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Current as at: Tuesday 25 March 2025
Contact page owner:
One Health
