February 25, 2025

Pig farms in Queensland, Australia, struck by Japanese encephalitis virus

Japanese encephalitis virus (JEV) has been detected at two pig farms in Queensland, Australia.

Biosecurity Queensland issued an alert confirming the detections of JEV in the state's south but did not provide specific locations or infection numbers, ABC News reports.

Although these are the first detections of JEV in animals in Queensland since July 2022, according to the alert, the disease is considered established in mainland Australia. JEV exploded into new regions of Australia in 2022, affecting over 80 swine breeding farms and causing significant production losses.

JEV is a flavivirus in the same family as West Nile virus, St. Louis encephalitis virus, and Murray Valley encephalitis virus. The virus is maintained in a cycle between mosquitoes and vertebrate hosts, mainly ardeid birds such as herons, egrets, and bitterns. There is spillover of JEV to other species including pigs, humans, horses, and other domestic animals. Humans and horses are considered dead-end hosts because they usually do not develop high levels of viremia, while pigs are an amplifying host.

Experts say clinical presentation varies by age and prior exposures in pigs. For adult pigs, it is primarily a reproductive disease, though affected adults may present with a non-specific fever. Sows can exhibit abortion, stillborn, fetal mummification, or subsequent production of weak piglets. Boars exhibit orchitis and infertility. In piglets, non-specific signs and wasting are evident as are neurologic disease and high mortality.

Queensland officials are encouraging people to make sure their vaccinations are up to date and to take extra mosquito control precautions. Humans can contract JEV from mosquitoes, however it does not spread human to human. JEV can be deadly in humans.

- Pork Business