Key points

• Langya does not present an imminent pandemic threat. It is important because it’s yet another warning about the way we are changing the world.
• Animal viruses spill over into humans all the time. Our actions are both increasing the rate at which this happens and increasing the chances of spillover to turn into global pandemic.
• Three-quarters of emerging viruses in the 21st century have jumped from animals, mostly from wildlife – among them HIV/AIDS, Ebola, SARS, MERS and now SARS-CoV-2.
• The rate at which these diseases emerge is also increasing decade by decade.

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G’day, Liam Mannix here. Welcome to Examine.

Remember Langya virus? The news cycle moves so fast these days you may have already forgotten it. New virus suddenly spreads in China, says one headline. China reports dozens of cases, says the next.

Calm down, say scientists. There have only been 35 reported infections since 2018, and there’s no evidence it spreads between humans. “There is no particular need to worry about this virus at the moment,” University of Sydney virologist Professor Edward Holmes says.

China is a major hotspot for zoonotic disease emergence.Credit:Bloomberg

Langya does not present an imminent pandemic threat – and so, quickly, the news cycle has moved on. Call it the panic-disinterest cycle.

But Langya is important because it’s yet another warning about the way we are changing the world.

Animal viruses spill over into humans all the time. Our actions are both increasing the rate at which this happens and increasing the chances of spillover to turn into global pandemic.

World governments are focused on dealing with the COVID-19 pandemic, but seem reluctant to invest in stopping the next one. They have forgotten the third part of the cycle: panic-disinterest-panic.

Langya

Langya is a henipavirus – a family that includes Australia’s most-famous zoonosis Hendra (more on that later). Chinese scientists picked it up as part of surveillance run on people who came down with unusual sicknesses in Shandong and Henan in 2018 (the name Langya comes from the home town of the first identified patient). Wider investigation revealed 35 patients sickened with the bug since then. The symptoms were fairly typical of a viral infection: fever, cough, fatigue.

Zoonoses are often seen in multiple animals, and that’s true for Langya: the researchers also found it in goats and dogs. The current thinking is shrews may be the natural host. All cases were unknown to each other with contact tracing not revealing any human-to-human transmission.

Langya is throught to have spread from shrews.Credit:AP

No human-to-human transmission, no recorded deaths. Of all the viruses we face, Langya does not appear to pose the most pressing threat – and indeed, by detecting it early and watching it closely, it’s being well-managed.

So rather than panicking, we should take this as a warning shot – an urgent call to deal with the increasing number of viruses that are spilling from animals to humans. Because the next one might not be so kind.

“We’re putting ourselves in increasingly risky situations,” says the University of Tasmania’s Dr Nick Fountain-Jones. “This trend is ongoing. No one is surprised by this. Just because of COVID-19, we shouldn’t think ‘oh we’re done with pandemics now’.”

Things are getting worse

Amid all the lab leak furore, what often gets missed is: scientists saw a pandemic coming. They even predicted one would emerge from wildlife in China, going from bats to intermediate animals and then into humans before spreading around the world on airliners.

Three-quarters of emerging viruses in the 21st century have jumped from animals, mostly from wildlife – among them HIV/AIDS, Ebola, SARS, MERS and now SARS-CoV-2. The rate at which these diseases emerge is also increasing decade by decade.

Langya neatly demonstrates how often this happens. Mostly these viruses go nowhere. But you only need one virus with the right collection of circumstances and adaptions to cause a pandemic. “We’re hyperconnected now,” says Fountain-Jones. “A spillover anywhere in the world can quickly radiate to major population centres and around the world because of global air travel.”

Why are viruses increasingly jumping from animal to humans? Because we are pressing down harder on the planet’s flora and fauna than ever before.

Animals have been around a lot longer than humans. Viruses have had a lot longer to evolve alongside them. Nearly every time scientists go hunting for viruses in animals, they come away with a dizzying number of never-before-seen pathogens. “All these interactions have been going on for millennia,” says Westmead Institute virologist Dr John-Sebastian Eden. “If you look you’ll find. Everything has a virus”

There are perhaps 87 million viruses that infect complex life. We live in our little cities while out there they thresh and infect and mutate. Humans suffer from just 219 virus species. The weight of numbers is vastly, vastly against us.

As we press up harder against animals, we increase our risks of catching their diseases. Brazil has made terrifying progress deforesting the Amazon and replacing it with farmland. Livestock on farms ends up cheek-to-jowl with stressed rainforest wildlife. Large herds of livestock can allow a virus to breed up to high levels and mutate before jumping into an unlucky farmer.

Left alone, forests actually provide a defence against zoonosis. Because there are so many different species living together, it’s hard for a virus to find enough hosts to become widespread. Turn forest into farmland inhabited by just a few species in large numbers and you’re making the virus’s job easy.

A section of Amazon rainforest stands next to soy fields in Belterra, Para state, Brazil. Credit:AP

Many diseases are spread from animal to human via bloodsucking insects – usually mosquitoes. While humans have been a curse for most of the natural world, they have been a blessing for mosquitoes, who have already greatly expanded their range and the range of the viruses they spread. Mosquitoes are cold-blooded – meaning they have a lot to gain from a warming world.

Consider two viruses we face in Australia. Hendra, named after the Brisbane suburb where it was first discovered in 1994, has a fatality rate of 60 per cent. Japanese encephalitis virus has killed five Australians this year.

Hendra jumps from flying foxes to horses and then into humans. As the climate warms and dries, eucalypts flower less, depriving the foxes of their food and forcing them to spread wider to find it. Hungry, stressed animals are more likely to both be infected and shed the virus. The foxes are now spreading south into the Hunter Valley, Australia’s thoroughbred racehorse breeding capital.

Hendra jumps from flying foxes to horses and then into humansCredit:Paul Rovere

JEV cycles between waterbirds and pigs via mosquitoes, and has been spreading as pig farming increases. Before 2022 it had only been seen in tiny isolated outbreaks in Australia. When authorities detected the virus here in March it was too late – the virus had been spreading through pigs undetected for some time. Last month NSW government scientists quietly conceded the virus was now likely endemic in feral pigs, meaning it is here to stay.

“We change the patterns of distribution of animals. We put animals and people in increasing contact. And viruses will mutate and jump species – as we’ve seen with COVID-19. It’s the next Hendra, the next COVID-19. We have to be vigilant,” says Dr Allison Stewart, an equine medicine specialist at the University of Queensland.

We aren’t doing enough to stave off the next pandemic

In a stroke of cosmic irony, Eddie Holmes actually visited Huanan Wildlife Market back in 2014 – he even passed the exact stall in the market’s zoo-like wildlife section where, years later, scientists would find significant traces of SARS-CoV-2.

Holmes remembers thinking at the time ‘this is where the next pandemic starts’. He suggested to his Chinese colleagues a surveillance station be set up, sampling wildlife and market workers. The idea was never acted on.

That’s a microcosm of a broader problem: globally, we aren’t doing nearly enough to stop the next pandemic.

“And it’s not until there’s huge numbers of deaths the money gets put into the situation,” says Stewart. She cites Hendra as the perfect example: authorities only started investigating when a human died.

“We do not know how many horses got sick and were euthanised before the disease was identified,” she says. “In rural Australia, there’s a lot of cases of animals that get sick. Is the case getting identified – or is the animal being buried without investigation?”

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