By Charlie Shield
After the novel coronavirus emerged in Wuhan, China in late December 2019, it didn’t take long for conspiracy theorists to claim it was made in a nearby lab.
The scientific consensus, on the other hand, is that the virus – SARS-CoV-2 – is a zoonotic disease that jumped from animals to humans. It probably originated in a bat, perhaps before crossing into another mammal.
While the virus was certainly not engineered in the lab, that doesn’t mean we played no role in the current pandemic. Human impact on natural habitats, biodiversity loss and ecosystem degradation make virus-spreading events much more likely, according to a major new study by Australian and US scientists.
The number of emerging infectious disease outbreaks has more than tripled every decade since the 1980s. More than two-thirds of these diseases originate in animals, and about 70% of them come from wild animals. Many of the infectious diseases we know of – Ebola, HIV, swine and avian flu – are zoonotic.
Aided by a hyper-connected global population, SARS-CoV-2 and the disease it causes, COVID-19, have also demonstrated how quickly modern epidemics can become pandemics.
While the speed at which COVID-19 has spread across the world has shocked many, scientists have long warned of such a pandemic.
By disrupting ecosystems, we have created the conditions that allow animal viruses to enter human populations, says Joachim Spangenberg, ecologist and vice-president of the Research Institute for a Sustainable Europe.
“We are creating this situation, not the animals,” Spangenberg told DW.
Deforestation, habitat encroachment
As people move deeper into wildlife territories to clear forests, raise livestock, hunt and extract resources, we are increasingly exposed to pathogens that normally never leave these places and the bodies they inhabit.
“We’re getting closer and closer to wild animals,” says Yan Xiang, a professor of virology at the University of Texas Health Sciences Center, “and that puts us in contact with these viruses.”
“As you increase human population density and increase encroachment on natural habitats, not just by people but by our domestic animals, you’re increasing the number of dice,” said David Hayman, professor of wildlife ecology. infectious diseases at Massey University in New Zealand. said DW.
But, in addition to increasing the probability of transfer, the disruption of ecosystems also has an impact on the number of viruses existing in nature and on their behavior.
Over the past century, tropical forests, which are home to around two-thirds of living organisms on the planet, have been halved. This profound habitat loss has ripple effects on the entire ecosystem, including the “parts that we tend to overlook – infections,” says Hayman.
In some cases, scientists have observed that when animals at the top of the food chain disappear, animals at the bottom of the food chain, such as rats and mice that carry more pathogens, tend to fill that gap.
“It’s not just about how many species we have in an ecosystem,” says Alice Latinne of the Wildlife Conservation Society, “it’s about which species.”
“Each species plays a different role in the ecosystem and sometimes if you just replace one species with another it can have a huge impact in terms of disease risk. And sometimes we can’t predict that,” a- she told DW.
Habitat changes can also force animals – and their pathogens – to move elsewhere, including areas populated by humans.
Latinne draws on the example of the emergence of the Nipah virus in Malaysia in the late 1990s, where deforestation drove fruit bats from their forest habitat to the mango trees of pig farms. Bats often carry pathogens that they don’t mind, but in this case, when the pigs came into contact with bat droppings and saliva, they became infected. The pigs then infected the farmers.
Evidence linking disruption of ecosystems to increased risk of transfer of new infections explains why, according to Spangenberg, experts talk about the importance of the “One Health” concept; the idea that animal, ecosystem and human health are all linked, and when one is out of balance, the others follow.
“Wet markets” selling produce, meat and live animals are another incubator for the emergence of infectious diseases. Scientists believe there is a strong possibility that SARS-CoV-2 emerged in a wet market in Wuhan, China.
Cramming stressed and sick animals together in cages is, in many ways, the “ideal setting” for incubating new pathogens, according to Spangenberg, and “a great way to transfer disease from one species to another.” For this reason, many scientists, including Spangenberg, argue that the world must, at the very least, introduce strict regulations for live animal markets.
That’s the message of Elizabeth Maruma Mrema, the UN’s biodiversity chief, who has called for a global ban on wildlife markets.
But as Mrema also pointed out, millions of people – especially in low-income communities – depend on the sources of food and income these markets provide.
That’s part of what makes solutions to preventing outbreaks complex, according to Hayman. Animal exploitation is one of them, he says. But “poverty, access to employment, the way people are treated in remote areas, the way people engage with food” also contribute to conditions that lead to fallout.
Even economically, Latinne believes, “we will be forced to change – because the cost of disease outbreaks and wildlife fallout will be far greater than the economic benefit of our exploitation of the environment.”
“We are part of nature — we are part of the ecosystem where our health is linked to the health of wildlife, the health of livestock and the health of the environment,” says Latinne. “We need to find a better way to live together safely.”
Republished with permission from Deutsche Welle.
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