As Australia’s climate changes, Japanese encephalitis spreads

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ECHUCA, Australia – A cloud of dust rises behind farmer Tim Kingma’s van as it winds down a gravel dirt road to a neat row of pig sties. The landscape is flat and low-key: dry ground, mostly treeless and patchy grass. On this farm in southeast Victoria, there are hundreds of flies and not a single mosquito visible. It is a world far from the verdant places where one would expect to find deadly tropical diseases.

Yet a month ago Kingma sows started giving birth to stillborn piglets. Some of the animals came out shriveled and withered, like little mummies. Alarmed, he called state authorities, who tested the animals and confirmed the diagnosis: Japanese encephalitis. Within weeks, he learned that a few dozen farms had been affected. More shockingly, the viral disease was killing Australians. At the beginning of this month, the authorities had counted 34 people cases and three deaths.

Japanese encephalitis is rare and usually asymptomatic. In 99% of cases, it passes through the body without causing symptoms. But of the unlucky 1%, almost a third die and about half of the survivors end up with permanent problems. There is no cure, and Australia is spending millions of dollars in a rush to import vaccine doses.

Public health professionals say the outbreak of Japanese encephalitis here is just the latest example of how global warming is helping the disease spread. Six years ago, melting permafrost in Siberia released frozen anthrax, which infected an indigenous community. In 2007, the tropical chikungunya virus was detected for the first time in Europe in two Italian villages and has since appeared in France. In the United States, Lyme disease cases have doubled in 30 years as warmer conditions create longer tick seasons. And in Australia, experts are warning that Japanese encephalitis could be the first of several illnesses to spread south.

Tim Inglis is the Head of Pathology and Laboratory Medicine at the University of Western Australia.

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“As climate change accelerates, we are going to be in a world of suffering,” he said, “with some of these diseases that in the past were limited to the tropics, spreading, as we begin to see it.

“Some of these diseases are not pleasant – and Japanese encephalitis is just one of the family.”

Japanese encephalitis is endemic in 24 countries in a sweltering swathe of Asia and the Pacific, from the northeastern tip of Australia to Japan, the Koreas, China and Southeast Asia., and India. It causes between 13,000 and 20,000 deaths per year.

The mosquitoes that carry it need pools of standing water, like those created by heavy downpours in the tropics, to breed. In February and March, Australia’s northeast coast was hit with record flooding – conditions that allowed the virus to travel hundreds of miles south and west via mosquitoes biting waterfowl, horses and, above all, pigs.

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It gained a foothold and moved beyond the floodplain in an outbreak encompassing four states: Queensland, New South Wales, Victoria and South Australia. Separately, over the past decade, it has traveled in the opposite direction, to the higher altitude regions of Tibet and Nepal.

Margo Andrae, chief executive of Australian Pork, said the pig farms were the “early warning system that something else was hitting Australia”.

“I think it took us all by surprise,” Inglis said. “We really didn’t expect to see things coming this far south, even with extreme weather conditions.”

Australia’s weather is governed by the multi-year rotating patterns of El Niño and La Niña – the former hot and dry with long droughts and wildfires, the latter cool and rainy with cyclones and floods. It is the La Niña years, when the planet warms up, that carry an increased risk of tropical diseases. A warmer atmosphere retains more moisture, which leads to more intense rainfall and flooding, allowing mosquito- and water-borne diseases to thrive.

Malaria is another disease that could encroach on Australia, Inglis said. He tracked the southward movement of melioidosis, a bacteria found in damp soil that can cause abscesses, seizures and death. Standing water appears to be a precondition for outbreaks of Buruli ulcer, a disease caused by flesh-eating bacteria that are increasingly present in southeastern Australia.

As for Japanese encephalitis, only one previous case on the Australian mainland was recorded at the northernmost point of the country two decades ago. But it has now appeared 2,000 miles to the south, in cooler, drier farmland.

David Kiefel, 61, is well into a second month on life support. A retiree in Corowa, a small town in New South Wales close to the Victorian state line, he now breathes through a tube and communicates by blinking. The only parts of his body he can move are his right hand, feet, neck, and facial muscles.

His doctors “decided there was nothing more they could do with him and David just needed time,” his wife, Jacquelene Monk, said. “We don’t know how much he will recover – or not – at this stage.”

Kiefel’s symptoms began with joint pain. Then headache and fatigue. He collapsed with brain swelling on February 19 and has been unable to breathe unaided since.

“He’s cognitive,” Monk said. “And he can read. I never thought he would be able to sit in a wheelchair, so I was quite stunned” when he did. “But he has advance directives – he wants quality of life.”

Across eastern Australia, government and council workers hang mosquito traps to collect specimens test the virus and track its spread. The federal government is rolling out vaccines for hog farm workers and other high-risk individuals. The key message from authorities is to avoid bites: wear insect repellent, cover yourself with loose clothing, drain or remove standing water.

Pig farmers are taking the same measures. The virus does not affect animal meat – it is not transmitted by eating pork or bacon – but it does affect production.

“I think Australians, in general, feel they need to be more careful and be more cautious and more aware of the unknown,” Andrae said. “Whether it’s floods, bushfires, now mosquitoes. Things are moving in Australia. Whether it’s the people, whether it’s the climate, whether it’s just that the risks are greater, the speed at which they move, we’ve just never seen before.

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In Corowa, Monk warns people to avoid mosquitoes. She wants the government to distribute free vaccines and investigate the spread of the virus.

It’s low and flat where she lives, and she’s noticed an increase in standing water after a summer of heavy rains. “I didn’t want anyone’s kid to end up like David,” she said. “The place he was bitten by a mozzie was in the city – it could have been at home.”

“We know climate change is affecting us here,” she added. “This is going to be a problem forever.”

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