10 May 2023

EXCLUSIVE: Japanese encephalitis virus detected in Cape York feral pigs

| Matt Nicholls
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Tropical Public Health Services director Dr Richard Gair.

CAPE York residents and tourists are being encouraged to cover up and wear insect repellent to avoid mosquito bites after the Japanese encephalitis virus was detected in feral pigs near Skardon River.

JEV cannot be spread from the pigs to humans, experts say, but are transmitted by mosquitoes.

Health officials said Cape York residents should not be alarmed by the presence of the virus in pigs, but should remain diligent.

A spokesperson from Biosecurity Queensland confirmed on Monday morning that a small number of feral pigs on Cape York had tested positive to JEV.

“Samples were taken as part of ongoing Northern Australia Quarantine Strategy surveillance activities,” they said.

“While JEV has been detected in feral pigs interstate, this is the first detection in Queensland.

“Landholders in the area and other stakeholders have been advised.”

Tropical Public Health Services director Dr Richard Gair said the risk to the public was minimal.

“It’s important to understand that JEV is transmitted to humans through mosquito bites only,” he said on Monday.

“It cannot be transmitted from human-to-human or direct from pigs, or by consuming pork or pig products.”


ROUTINE testing for Japanese encephalitis virus led to its discovery in Cape York in what is the first case of detection in feral pigs in Queensland.

Biosecurity Queensland, through its Northern Australia Quarantine Strategy, has been surveilling Cape York for JEV and other viruses and diseases since the 1990s.

While there have been a number of JEV cases in humans in Australia over the years, transmission is rare.

“It’s important to understand that JEV is transmitted to humans through mosquito bites only,” said Tropical Public Health Services director Dr Richard Gair.

“It cannot be transmitted from human-to-human or direct from pigs, or by consuming pork or pig products.

“The vast majority of 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 (encephalitis), characterised by sudden onset of vomiting, high fever and chills, severe headache, sensitivity to light, neck stiffness and nausea/vomiting.

“The best defence against mosquito bites is to avoid being bitten in the first place.”

Biosecurity Queensland said it was working with other states and territories, as well as local industries, to minimise risks of transmission.

“The normal lifecycle of Japanese encephalitis virus is between waterbirds and mosquitoes,” a spokesperson said.

“Infected mosquitoes can transmit the virus to pigs and people through bites. The virus is not transmitted from person to person.

“If producers see any of signs of the JEV, they should immediately contact a veterinarian, then Biosecurity Queensland on 13 25 23.”

Earlier this year, there were a number of JEV cases across the country after the virus spread from mosquitoes at piggeries in southern states.

In March, Australia’s acting chief medical officer Dr Sonya Bennett declared the JEV situation a Communicable Disease Incident of National Significance.

She determined a national approach was required in relation to the coordination of health policy, interventions and public messaging.

Around 40 cases of JEV have been detected in humans in Australia this year with five deaths.

The number of JEV cases and deaths reported in 2022 is unusually high as compared to only 15 cases notified in Australia in the 10 years prior.

Of those 15 cases, only one case was acquired in Australia, with the remaining 14 cases acquired overseas.

Dr Gair said Cape York residents should not feel unsafe but encouraged everyone to take precautions.

“Measures to prevent mosquito bites include regularly applying insect repellent containing Diethyl Toluamide (DEET), Picaridin; wearing loose, light-coloured clothing to cover up arms, legs and feet; and using other insecticide-based mosquito control devices where possible when outside,” he said.

“Mosquito bites can be experienced at any time of day, but some species are most active at dusk and dawn.

“It’s also important to ensure flyscreens are in good order so mosquitoes can’t enter your home easily.

“JEV is a nationally notifiable disease in both humans and animals.”

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