Unprecedented outbreak: Japanese encephalitis virus hits Australian pig farms

Chris Richards of Apiam AnimalHEALTH in Australia highlighted the wide range of symptoms observed, including prolonged gestation periods, stillborn piglets, congenital anomalies and neurological problems. Particularly concerning about this outbreak was the geographical spread of affected farms, some of which were separated by thousands of kilometres.

The confirmation of JEV in south-eastern Australia prompted an immediate response, treating it as an outbreak of foreign animal disease (FAD). In the following months, more than 80 pig farms reported confirmed cases, indicating the seriousness of the situation.

Among the most alarming symptoms was an extended gestation period in some sows, leading to the birth of stillborn piglets. This phenomenon affected a variable number of piglets in each litter.

Congenital abnormalities in stillborn piglets further complicated the outbreak, with severe conditions such as arthrogryposis and brachygnathia observed. Neurological abnormalities including cerebral and cerebellar aplasia, hydranencephaly, and congenital tremors in live-born piglets painted a grim picture of the virus’ impact.

JEV, a flavivirus endemic to east and southeast Asia, has never been detected in southeastern Australia. Waterfowl serve as its vectors and pigs as amplification hosts. 

Despite the unprecedented nature of the outbreak, the Australian pig industry’s response was swift and coordinated. Previous exotic animal disease planning, coupled with strong partnerships between producers and government officials, enabled decisive action to be taken to combat this unexpected threat.

The emergence of Japanese encephalitis virus in Australia serves as a stark reminder of the ongoing challenges posed by zoonotic pathogens and the critical importance of preparedness and collaboration in mitigating their impact.