Japanese encephalitis (JEV) has been discovered for the first time in feral pigs in far north Queensland.
The virus is primarily spread by mosquitoes feeding on infected animals and does not usually spread directly from animal to animal (i.e. it is not considered contagious). Only certain types of mosquitoes can become infected with the Japanese encephalitis virus.
Pigs with the infection do not transmit the infection to other animals but may infect mosquitoes if bitten while they still have the virus in their blood.
The ABC reported the discovery of the mosquito-borne disease follows an outbreak across four states that is linked to the deaths of five people so far this year.
Biosecurity Queensland said a small number of feral pigs in the Skardon River area in the western Cape York Peninsula had tested positive for the disease following routine testing.
Tropical Public Health Unit director Richard Gair said JEV had not been detected in any people in the area.
“It is an isolated area and the mosquito numbers are very low,” Dr Gair said.
“It is only quite rarely that humans will get the disease, and if they do get it, they aren’t infectious.
“Most human infections of JEV cause no symptoms or mild symptoms such as headache or fever.
“A person with severe disease may present with inflammation of the brain, characterised by sudden onset of vomiting, high fever and chills, severe headache, sensitivity to light, neck stiffness and nausea and vomiting.”
Five people, including one in Queensland, are reported to have died of the disease this year with more than 40 human cases detected across the country.
Clinical signs of Japanese encephalitis in pigs
Adult sows do not typically show overt signs of disease, but if infected before 60-70 days of pregnancy often either abort or give birth to mummified and stillborn or weak piglets, some with neurological signs. In a naïve population, litters from sows and gilts would be expected to be equally affected. Boars, if present on-farm, may experience infertility and swollen, congested testicles.
I suspect my farmed pigs have Japanese encephalitis
Japanese encephalitis is a notifiable exotic disease. If you suspect Japanese encephalitis in your pigs , immediately contact your local Agriculture staff.