The origin of the coronavirus wreaking havoc around the world remains a source of mystery and controversy.
Scientists generally agree that COVID-19 is a zoonotic disease. That means it jumped from animals to humans, most likely from horseshoe bats to people perhaps near the city of Wuhan, in China.
But, how exactly did people come to such close contact with horseshoe bats and trigger this global pandemic? And what does this fatal interaction between humans and wildlife say about the broader need to separate wild animals and people for the survival of both?
Author Debora MacKenzie offers some answers to these questions in her new book titled, “Covid-19: The Pandemic that Never Should Have Happened and How to Stop the Next One.”
It’s not that people in Wuhan eat horseshoe bats. They do not. But MacKenzie’s research points to the widespread collection from caves of bat manure – or guano – which is sold as a traditional Chinese medicine. The guano is marketed and applied to people’s eyes with dubious claims that it improves night vision.
“People are using this to make an eye remedy,” MacKenzie said. “Now, your eye is probably where Covid-19 infects a lot of people. It’s got a lot of the protein – the ACE2 protein -- that acts as the receptor of the virus. It’s got a lot of that. If you were to do a liquid extract on this dried bat poop powder, and put it in your eye, it would be a pretty good way of getting a virus…. Or maybe the person who collects the guano got sick and passed it on from person to person.”
Around the world, bats have been the hosts for a wide variety of deadly diseases in people – including Ebola, SARS, Hepatitis C, and rabies. This is in part because bats do not have an immune response to these viruses and are not killed by them. This means bats can carry a large number of pathogens throughout their lives, MacKenzie said.
“There are hundreds and hundreds of viruses – you just have to look in a bat,” MacKenzie said. “The thing is, a bat just has to become infected by it once. And if the virus can do it, it will hang around, because basically a bat does not kill cells that have viruses in them, the way we would. In fact, they turn off that whole inflammation response that our whole immune systems do.”
However, if we are looking for a way to prevent the spread of disease, humans can not just kill off bats because bats are a critical part of the ecosystem that we rely on. Bats spread the seeds that allow rain forests to grow, for example. And bats eat many of the caterpillars and moths that otherwise devastate our food crops.
Instead, MacKenzie argues, humans need to back off and give space to bats and other wildlife that carry viruses. Every time we push further into jungles or caves – or clear-cut more forests to build farms and homes – we are putting ourselves at risk of picking up pathogens that are new to humans and can spread among us like wildfire.
“You need conservation in order to maintain human health,” MacKenzie said. “Because you need the bats. But you also need them not roosting over your pig sties. You know, so you’ve got to maintain enough forests for the bats to live in, so they don’t have to bother you. They can stay in their forests, they are fine. And we get the ecosystem services that they provide, and we’re fine. And we don’t catch their viruses.”
So for our own welfare, humans need to start protecting and respecting the welfare of animals.