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Deforestation isn't just an environmental problem. It's a public health crisis.

Posted at 7:36 AM, Apr 08, 2020

Deforestation, habitat loss and wildlife poaching aren't just environmental issues. They're among the driving forces behind the rise in global infectious disease outbreaks -- and likely contributed the current pandemic.

That's according to scientists who've been sounding the alarm for decades, warning that as we encroach on wildlife to establish new farmland, build mining operations or just make room for growing cities and towns, the more likely it is we'll come into contact with wild animals harboring deadly pathogens.

"COVID-19 is not surprising because we know how these things happen," said Aleksandar Rankovic, a senior research fellow working on biodiversity governance at the Paris-based Institute for Sustainable Development and International Relations. "We know the risk factors for new disease transmission, and we know that they have been increasing rather than decreasing. I'm surprised people are so surprised."

A study published Tuesday in Proceedings of the Royal Society B finds a direct link between hunting, trade, habitat degradation and urban sprawl and the increase of what scientists call "spillover" events, in which viruses circulating in animals like bats and monkeys jump to humans.

"We found that the species specifically that declined because of exploitation through trade and hunting and those species that declined specifically due to habitat loss had higher spillover risk," said lead author Christine Kreuder Johnson, project director of USAID PREDICT and director of the EpiCenter for Disease Dynamics at the One Health Institute, a program of the UC Davis School of Veterinary Medicine.

According to Johnson and a growing community of concerned scientists, the more we endanger wild species, the more we endanger ourselves.

"When you destroy habitats, you increase vastly the amount of contact that human populations will have with different species, and some of these species will host a range of viruses," Rankovic added.

Experts agree that as the planet's hot zones -- typically tropical climates along the equator -- are suddenly disrupted by development, workers come into too-close contact with wild species and pass along viruses to nearby villages and towns, from there to larger cities.

Recent history is rife with spillover events. HIV, SARS and Ebola all can be traced back to animal hosts living in ecosystems scientists refer to as highly "biodiverse."

And experts now believe SARS-COV-2, the virus responsible for the deaths of more 1 million people worldwide from COVID-19, originated in bats in Southwest China and eventually made its way to a wet market in Wuhan, likely through an intermediate host.

"In the case of COVID-19, bat caves are abundant in Southwest China," explained Peter Daszak, president of the EcoHealth Alliance. "People are developing a lot of new towns in that region, with a lot of high-speed train lines. We are going to see more pandemics like this as long as such rampant development continues."

Experts have said that the more we push into rich, biodiverse habitats, the more frequent spillover events will occur. Humans have a significant impact on about 75% of the Earth's land, 50% of the planet's freshwater ecosystems and 40% of all ocean environments, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services 2019 Global Assessment.

And the more interconnected we become as a global economy, with tens of thousands of international flights per day, the less likely it is spillover events will be contained to the regions in which they emerged.

Those studying the linkages between pandemics and biodiversity loss say there are three major factors driving the increase in spillover events: massive deforestation, industrial-scale animal farms too close to wild habitats and the hunting wild animals, either for profit or food.

There are 1.7 million unknown viruses that have the potential to infect people, according to Daszak.

"To say, 'Don't worry, we'll design a vaccine to fix the problem,' is not a solution," Daszak added. "You can only design vaccines against pathogens you know. If we have 1.7 million that we don't know, that sort of thinking doesn't help."

While it's too late to stop the 2019 novel coronavirus from spreading beyond China, experts have said political leaders across the globe still could come together to put in place policies to help prevent the next outbreak. Although global pandemics and the current biodiversity crisis are considered different problems with different potential solutions, experts have said they should be considered together.

"Let's treat pandemics like a global public health threat," Daszak said. "Biological diversity and healthy ecosystems is the insurance plan that we must prioritize, as it protects us against a variety of risks -- including pandemics."