Health authorities are on alert after confirming a "highly probable" case of Japanese encephalitis virus (JEV) in a NSW resident.

Residents across regional areas, and particularly in the western and southern areas, to be vigilant and safeguard themselves against mosquito bites. 

The news came just hours after NSW Local Land Services issued a warning that JEV had been detected and urging landholders to report any unusual symptoms in livestock, and in pigs in particular, to the Emergency Animal Disease Hotline.

JEV is a mosquito-borne virus and can cause severe neurological illness with headache, convulsions and reduced consciousness in some cases. 

The virus has no specific treatment.

The infected person is a resident of the NSW-Victoria border region and last night was in intensive care but in a stable conditions. 

NSW Health advises that several more patients are undergoing testing and more cases are expected to be confirmed. 

Locally acquired cases of JEV have never previously been identified in NSW in animals or humans. JEV is usually only found in far northern Australia and neighbouring countries. 

What is JEV?

JEV is a viral illness spread by mosquitoes. It can infect animals as well as humans, and has been confirmed in samples from a number of pig farms in regional NSW.  

The virus cannot be transmitted between humans, and it cannot be caught by eating pork or pig products. 

Dr Marianne Gale, NSW Health Acting Chief Health Officer, said the best way to avoid infection is to avoid being bitten by mosquitoes – an urgent message given the current moist to wet conditions across much of the state.  

“NSW Health is cautioning people undertaking outdoor activities such as camping and fishing to carefully consider their plans. This is especially important for people planning activities near waterways or where mosquitoes are present, particularly the Murray River and its branches,” Dr Gale said. 

“People should be particularly vigilant given the recent wet weather conditions, which have led to very high mosquito numbers that may increase further in the coming days and weeks.”  

NSW Health is working closely with the NSW Department of Primary Industries and other state and territory agencies to determine the extent to which the virus is circulating, through animal testing and mosquito monitoring.  

Mosquito control activities are being carried out in the vicinity of farms where pigs are confirmed to have been infected by JEV and NSW Health is arranging vaccination of workers on affected farms. 

Protecting yourself against JEV 

Mosquito control activities are being carried out in the vicinity of farms where pigs are confirmed to have been infected by JEV and NSW Health is arranging vaccination of workers on affected farms. 

Simple actions you can take to avoid mosquito bites include:  

• Avoid going outdoors during peak mosquito times, especially at dawn and dusk.  

• Wear long sleeves and pants outdoors (reduce skin exposure). Also wear shoes and socks where possible. There are insecticides (e.g. permethrin) available for treating clothing for those spending extended periods outdoors.

• Apply repellent to all areas of exposed skin, especially those that contain DEET, picaridin, or oil of lemon eucalyptus which are the most effective against mosquitoes. The strength of a repellent determines the duration of protection with the higher concentrations providing longer periods of protection. Always check the label for reapplication times.  

• Reapply repellent after swimming. The duration of protection from repellent is also reduced with perspiration, such as during strenuous activity or hot weather so it may need to be reapplied more frequently. 

• Apply the sunscreen first and then apply the repellent. Be aware that DEET-containing repellents may decrease the sun protection factor (SPF) of sunscreens so you may need to re-apply the sunscreen more frequently.  

• For children in particular - most skin repellents are safe for use on children aged 3 months and older when used according to directions, although some formulations are only recommended for children aged 12 months and older - always check the product. Infants aged less than 3 months can be protected from mosquitoes by using an infant carrier draped with mosquito netting that is secured along the edges.  

• Be aware of the peak risk times for mosquito bites. Avoid the outdoors or take preventive actions (such as appropriate clothing and skin repellent) between dawn and dusk when most mosquitoes become active, especially close to wetland and bushland areas.

• Mosquito coils and other devices that release insecticides can assist reducing mosquito bites but should be used in combination with topical insect repellents. 

• Reduce all water holding containers around the home where mosquitoes could breed. Mosquitoes only need a small amount of liquid to breed.  

Further information on mosquito-borne disease and ways to protect yourself available here.

Fact sheets on specific mosquito-borne diseases, including Japanese encephalitis Ross River virus and Barmah Forest virus, are available here.