Japanese encephalitis

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JE is a seasonally endemic and is notifiable because it can transfer to humans, not because of a significant threat to pig populations.
Disease occurs most commonly in pigs and horses. Few species are thought to play a significant role in the natural transmission of JEV – most commonly waterbirds and pigs. Humans can also be infected.
Japanese encephalitis (JE) is an acute mosquito-borne viral disease that can cause abortion and mummified fetuses, as well as fever and encephalitis (inflammation of the brain), in pigs and horses.
Evidence of exposure to JEV and/or infection has been detected in a wide range of animal species, including waterbirds, pigs, equids (horses and donkeys), cattle, sheep, goats, water buffalo, chickens, ducks, dogs, cats, monkeys, raccoons, rodents, insectivorous bats, flying foxes, snakes, lizards and frogs.

Japanese encephalitis virus is not spread directly from pigs to people, and it does not spread from pig to pig. The virus is primarily spread by mosquitoes.
In pigs, the most common clinical signs are mummified and stillborn or weak piglets, some with neurological signs.
Piglets infected after birth can develop encephalitis which presents as paddling or other neurological signs in the first six months of life. In other cases, wasting, depression or hindlimb paralysis may be seen in suckling piglets and weaners.
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 horses many cases are subclinical, meaning that they can be infected but now show signs of the disease. Most clinical disease is mild, however more severe encephalitis can occur which may be fatal.
Signs include an elevated temperature, jaundice, lethargy, anorexia and neurological signs which can vary in severity.
Neurological signs can include incoordination, difficulty swallowing, impaired vision, and rarely the horse becomes over excited.
While reports of the disease in other species are rare, overseas the disease has been reported in donkeys.
Horses are known to be a ‘dead end host’. They do not carry a blood infection that will reinfect mosquitoes.

Call the 24-hour Emergency Animal Disease Hotline on 1800 675 888 if you suspect JE on your property.

Alternatively contact your local vet in the region or district government vet.

Pig producers are asked to be highly vigilant for signs of this disease and report unexplained pig abortions or stillbirths.
Many piggeries operate under the national Australian Pig Industry Quality Assurance program which sets high biosecurity and hygiene standards for commercial piggeries.
People working with pigs, including those who may have a small herd or pet, should take steps to control mosquitoes, as well as continue to use effective biosecurity measures.
You can find out more at farmbiosecurity.com.au and the National Pork Biosecurity Manual which provides in-depth detail on biosecurity practices and management in piggeries.
Australian Pork Limited (APL) are providing excellent support and advice to affected piggeries across the regions where outbreaks have occurred

Horse owners can also put measures in place to help their horses avoid mosquito bites. During hotter months put a light cotton rug on them, a fly mask, and if the horse allows, apply a safe insect repellent. Do not spray the repellent around or above their eyes.
The Australian mosquito that transmits JE feeds at night and is reluctant to enter dwellings, so stabling horses between dusk and dawn is a valuable action.
Additional measures to protect stabled horses are listed in the JE AUSVETPLAN Response Strategy, including topical treatment with insect repellents.
Rugging and hooding with lightweight permethrin fabric may help protect horses not stabled overnight.

The Consultative Committee on Emergency Animal Diseases provides technical and scientific advice in response to exotic animal disease outbreaks. The Committee is chaired by Australia’s Chief Veterinary Officer and comprises the Chief Veterinary Officers from each state and territory, other specialists from government, Animal Health Australia, and representatives the pig and horse industries. The Australian Government Department of Health is also participating.
The National Management Group (NMG) consists of Chief Executive Officers from government agencies responsible for agriculture and affected industry organisations. It is chaired by the Secretary of the Australian Government Department of Agriculture, Water and the Environment. Animal Health Australia is a non-voting member.
NMG makes decisions on whether to support national eradication programs for disease outbreaks under the Emergency Animal Disease Response Agreement. NMG considers recommendations provided by the consultative committee before making decisions on whether a pest or disease is technically feasible to eradicate.
The Emergency Animal Disease Response Agreement is a formal legally binding agreement between Animal Health Australia, the Australian, state and territory governments, and national livestock industry bodies. The Agreement covers the management and funding of nationally agreed responses to emergency animal disease incidents.