With the onset of summer in Australia, New South Wales (NSW) Health has issued a warning urging residents to safeguard themselves against mosquito bites. This advisory follows the early detection of mosquito-borne viruses that pose a risk of brain swelling, notably in regions across NSW.
On December 4, 2025, a press release from NSW Health confirmed the first detection of the Japanese Encephalitis virus (JEV) for the 2025-2026 summer season. The virus was identified in mosquitoes from the Horsham Rural City Council area in Victoria, northwest of Melbourne. Currently, 60 Local Government Areas in NSW are considered at risk for the mosquito-transmitted JEV.
Early Detections Raise Alarm
In addition to JEV, the Kunjin virus has been detected in Western NSW, specifically in Cowra, through a sentinel chicken blood sample as part of NSW Health’s routine surveillance. These early detections have raised concerns among health officials.
Dr. Stephen Conaty, Director of Health Protection at NSW Health, expressed his concerns in a press release. “Mosquito numbers will likely increase with warmer weather, and we remind everyone in NSW to protect themselves against mosquito bites, which can cause diseases such as Japanese Encephalitis and Murray Valley Encephalitis, and infection with Kunjin virus, Ross River virus, and Barmah Forest virus,” he stated.
“There is a safe, effective, and free vaccine (JEspect / Ixiaro) to protect against Japanese Encephalitis (JE),” Dr. Conaty added.
Vaccination and Prevention Strategies
The JE vaccine is available free of charge to individuals residing or working in the 60 specified LGAs west of the dividing range and in northern NSW, as well as for those in certain high-risk occupations. The vaccine can be obtained through General Practitioners, Aboriginal health services, and pharmacists, although providers may require advance notice to order the vaccine and may charge a consultation fee.
For those with ongoing exposure risks, a booster dose may be recommended one to two years after completing the primary vaccination course. The U.S. Centers for Disease Control and Prevention (CDC) also advises international travelers to consider JEV vaccination when visiting areas such as Australia’s Murray River and the Outer Torres Strait Islands.
Challenges with Non-Vaccine-Preventable Viruses
While JEV has a vaccine, the Kunjin virus does not. Currently, there is no vaccination or specific treatment available for Kunjin virus in Australia. The best preventive measure is to avoid mosquito bites, particularly during peak activity times between dusk and dawn, according to NSW Health.
This situation underscores the importance of public awareness and preventive measures, especially as millions of international tourists are expected to visit NSW during the summer months. The health department emphasizes the need for protective clothing, insect repellent, and mosquito-proofing living areas.
Looking Forward: Health Implications and Recommendations
The early detection of these viruses highlights the need for ongoing vigilance and public health preparedness. As climate patterns shift and potentially extend the mosquito season, health officials are urging communities to remain proactive in their defense against mosquito-borne diseases.
Efforts to educate the public on the risks and prevention strategies remain crucial. The health department plans to continue its surveillance and public information campaigns to mitigate the impact of these viruses.
As the summer progresses, NSW Health will provide updates and guidance to ensure the safety and well-being of residents and visitors alike. The situation serves as a reminder of the broader implications of climate change on public health and the necessity for adaptive strategies in response to emerging health threats.
