As mosquito numbers decrease over winter and migratory water birds move north over winter, the risk of Japanese encephalitis infection in pig, horses, other livestock and people is reduced.
The cooler months present an opportunity to:
Remember, if you see any unusual signs of disease or death in your pigs, horses or other livestock, report it immediately to the Emergency Animal Disease Hotline on 1800 675 888.
Japanese encephalitis (JE) virus is a mosquito borne virus, a flavivirus, that may infect a range of species including waterbirds, pigs, horses and donkeys, cattle, sheep, goats, water buffalo, chickens and others. These animals act as sentinels (or indicators), highlighting the presence of the disease in the environment.
Japanese encephalitis virus is a serious, emergency animal disease of animals. It is notifiable in Australia, meaning any suspected cases need to be reported immediately.
Japanese encephalitis virus (JEV) is a mosquito-borne viral disease, which is maintained in nature by transmission cycles involving Culex sp. mosquitoes, certain species of wild and domestic birds. Pigs are a known amplifying host of the JE virus.
Horses may become infected, but they do not spread the virus to other horses, animals or people. They are a dead-end host.
People may also become infected resulting in encephalitis (inflammation of the brain) and death in severe cases.
Pigs: If you see any unusual signs of disease or death in your pigs or suspect JE in pigs, you must report it to your Local Land Services District Veterinarian immediately on 1300 795 299 or call the 24-hour Emergency Animal Disease Hotline on 1800 675 888.
Horses: Due to the clinical similarity to Hendra virus infection, a sporadic but serious zoonotic disease, it is important to take appropriate precautions when assessing, sampling, and treating affected horses.
If you see any unusual signs of disease or death in your horse(s) or you suspect JE in horses, you must report it to your veterinarian or call the 24-hour Emergency Animal Disease Hotline on 1800 675 888.
Australia has a number of mosquito species that are capable of transmitting the virus. This is the main route of infection. Few additional species play a significant role in transmission, mainly waterbirds and pigs, and few species show clinical signs of disease.
The primary mechanism of spread of JEV between hosts is by bites from infected mosquito vectors. Transmission is believed to be maintained in mosquito–waterbird or mosquito–waterbird–pig cycles (see Figure 1).
Waterbirds, particularly wading birds, such as herons and egrets, are the main natural reservoirs of JEV and are important amplifying hosts.
Horses are a dead-end host, while they can become infected with JE, they cannot pass on infection to other horses or people. People do not get infected from horses.
In 2022, outbreaks of JE were reported in domestic pigs and people in Queensland, New South Wales, Victoria and South Australia. In addition, cases of JE were reported in the Northern Territory in a number of feral pigs as part of their NAQS program.
In NSW, all confirmed cases of JE in pigs were detected in inland regional areas that were predominantly concentrated along water courses and west of the Great Dividing Range.
In addition, evidence of JE virus infection was detected in horses from the North Coast, Hunter, Greater Sydney, Central West and Riverina Local Land Services regions of NSW.
Japanese encephalitis remains a notifiable disease in NSW.
This means that owners, managers or people working with pigs and horses must continue to report all suspicion of disease by immediately reporting to the Emergency Animal Disease Hotline on 1800 675 888.
All owners or managers of susceptible animals, whether for production or companionship, have a responsibility, a biosecurity duty, to manage the risk of Japanese encephalitis introduction and spread on their property. This can be done by developing and actioning a mosquito management plan, based on environmental and operational factors to control mosquitoes and manage the risk of JE for pig, horse and public health management.
The national policy is to control JE in domestic animal populations to support public health agencies and the affected industries. More information about national disease response activities is available at Outbreak. Strategies include:
Currently, there is no effective treatment for JE in animals in Australia.
The best way to protect your pigs, horses and your local community is by developing and implementing an integrated mosquito management plan. This involves targeting all stages of the mosquito life cycle to break the breeding cycle (see Figure 2).
If you observe unusual signs of disease, behaviour or death consistent with JEV, and require assistance, contact your Local Land Services District Veterinarian (DV) on 1300 795 299 or the Emergency Animal Disease Watch Hotline on 1800 675 888 for assistance or advice.
The Elizabeth Macarthur Agricultural Institute has provided the following advice for taking and submitting sample for JE exclusion.
Whole fresh aborted or stillborn foetuses are also suitable for submission where samples can't be collected on farm.
Expect 12-48 hours after sample arrival at the laboratory for PCR results.
Adult non-pregnant sows show no obvious signs of infection. JE is associated with reproductive failure in pigs, with 50–70% losses reported in affected populations:
Adult sows do not typically show overt signs of disease. If boars are present on farm, they may experience infertility and oedematous, and congested testicles.
In pigs, clinical signs include:
While Japanese encephalitis has an incubation period of up to 21 days in pigs it is typically 1-3 days. The incubation period is the period of time from when the pig is bitten by an infected mosquito to showing the first clinical signs of JE.
Pigs (feral and domestic) develop high levels of infection and are also major amplifiers of the virus.
Outbreaks in previously unexposed pig populations typically consist of 2 cycles:
If you observe signs of disease or death consistent with JE virus, contact the Emergency Animal Disease (EAD) Hotline on 1800 675 888 for advice.
Either your private veterinarian or a Local Land Services District Veterinarian will coordinate collecting samples for testing. Samples required for testing include:
More information on clinical presentation and investigation can be found at:
The best way to protect your pigs is by developing and implementing an integrated mosquito management plan. This involves a targeting all stages of the mosquito life cycle to break the breeding cycle.
Effective mosquito management on-farm includes:
In May 2022, evidence of JE virus infection was detected in horses from the North Coast, Hunter, Greater Sydney, Central West and Riverina Local Land Services regions of NSW.
Australia has a number of mosquito species that are capable of transmitting the virus. This is the main route by which people and other animals, including horses, become infected.
Due to the clinical similarity to Hendra virus infection, a sporadic but serious zoonotic disease, it is important to take appropriate precautions when assessing, sampling, and treating affected horses.
If you observe unusual signs of disease, behaviour, or death in your horse(s), contact your veterinarian or the Emergency Animal Disease Watch Hotline on 1800 675 888 for assistance or advice.
Horse owners are encouraged be aware of the clinical signs of JE:
Japanese encephalitis has an incubation period of 4-14 days in horses.
While reports of the disease in other species are rare, overseas, the disease has been reported in donkeys.
People do not get infected from horses. Horses are a dead-end host, that is, they do not transmit the virus to other horses, animals, or people.
Horse owners are encouraged to reduce the risk of horses being exposed to mosquitoes, after the confirmation of Japanese encephalitis in pigs New South Wales in 2022.
Stabling horses between dusk and dawn could help, as the mosquito most likely to carry diseases of concern is a night-time feeder that stays outdoors.
While there have been no confirmed cases of JE in horses in NSW, horse owners are encouraged to take mosquito risk prevention measures where possible, including:
There has been considerable impact on both human health, animal industries as well as socio- economic impacts.
For those livestock owners who have had stock affected by JE, the impacts may be far reaching and beyond production losses alone. There are a number of Farm Business and Wellbeing resources that are available to support pig owners and producers affected by JE.
The Rural Financial Counselling Service (RFCS) NSW are available to help affected producers manage the financials at play and lessen the stress. RFCS NSWs completely free services specialise in helping primary producers with the risk management and regulatory requirements that are in place to manage JE.
RFCS NSW has local counsellors who are experienced in guiding farmers though the toughest of conditions, come flood, drought, mouse plagues or emergency disease events.
For more details or to contact support staff, call 1800 319 458 or visit www.rfcsnsw.com.au
FarmHub connects Australian farmers to a range of helpful services and support. Services include farm business assistance to help farmers navigate financial challenges, as well as mental health tools and services designed to strengthen wellbeing.
The Farm Business Assistance directory brings together assistance and support options for you and your farm business from a wide range of Government and private sources.
For more details, visit https://farmhub.org.au/explore-assistance/
The Rural Adversity Mental Health Program (RAMHP) has 20 Coordinators based across regional, rural and remote NSW. RAMHP Coordinators educate and connect individuals, communities and workplaces to mental health services and support.
RAMHP can help link people to local mental health support, as well as offer training to workplaces and community groups about mental health and wellbeing in times of adversity.
For more details, or to find a RAMHP coordinator near you, visit www.ramhp.com.au
FarmHub connects Australian farmers to a range of helpful services and support. Managing a serious disease event, like Japanese encephalitis, and other challenges, it is more common for people to experience distress, including anxiety and depression.
With a little help, you can employ tools and strategies that support stronger mental health and wellbeing – making you, your family and your business more resilient.
The Farm Hub provides a Mental Health Resource hub, summarising a range of services that are available to help strengthen mental wellbeing for the farming community.
For more details, visit https://farmhub.org.au/mental-health/