Feral pigs found infected with Japanese encephalitis in NSW

These diseases can be transmitted from feral pigs to humans, domestic pets and livestock, with serious impacts on health and agriculture.

Japanese encephalitis is caused by the Japanese encephalitis virus (JEV). It is spread through bites from mosquitos, which become infected through biting infected pigs and waterbirds.

Local Land Services is collaborating with NSW DPI's Wildlife Disease Surveillance project to actively monitor diseases in feral pigs across the state. The widespread potential for disease highlights the need to control feral pigs and minimise the risk to landholders and their animals.

72% of sample sites showed feral pigs have been infected with the virus that can cause Japanese encephalitis and Murray Valley encephalitis (flaviviruses).

Brucellosis (Brucella suis) was detected in feral pigs at 39% of sites, mainly in the North-West and Northern Tablelands regions.

Of the 21 sites sampled, infection with Leptospira interrogans (serovars pomona and tarassovi, causative agents of leptospirosis) was detected at 82% of sites.

Leptospirosis is considered the most common bacterial infection in feral pigs. Landholders should also consider vaccinating their livestock, carrying out feral pig control, washing their hands before eating and wearing protective clothing such as gloves when handling at risk animal materials.

Although there is no vaccine for brucellosis, landholders can help minimise the spread by preventing contact with feral pigs, practicing good hygiene and protection, not feeding feral pig meat to dogs and controlling local feral pig populations.

Feral pig hunting dogs are at high risk of contracting the disease and potentially transmitting it to other dogs and humans.

JEV is endemic to parts of Asia and the Torres Strait region of Australia. JEV has now also been detected in humans, animals and mosquitos in mainland Australia.

Infection in humans is most commonly asymptomatic, but on rare occasions it can result in severe disease and even death.

Animals can be infected with JEV but they cannot transmit the virus to humans. It cannot be transmitted from human to human, or by eating meat from an infected animal.

Australia experienced an outbreak of JEV in domestic pigs in 2022, with detections in over 80 piggeries in Queensland, New South Wales, Victoria and South Australia.

Australia's Acting Chief Medical Officer at the time declared the Japanese encephalitis virus outbreak a Communicable Disease Incident of National Significance, following the detection of human cases of JEV across multiple states on mainland Australia.

Prior to this, JEV was thought to be limited to seasonal transmission in the Torres Strait Islands and (occasionally) Far North Queensland.

For support in controlling feral pigs, landholders can contact their local biosecurity officer who has the knowledge and experience to assist.

Call 1300 795 299 or visit lls.nsw.gov.au/feral-pigs