JOHN YANG: The search for the exact origin of COVID-19 is highlighted the risks of viruses transmitted by certain species of bats.

To the wild they can withstand virus that kill another animals and the virus can incubate in bats and spread to other animals and humans.

As Ali Rogin explains, today, humans and bats are interacting more than ever.

ALI ROGIN: Global industrialization continues to reduce the amount of the world untouched by humans.

That means species like bats are no longer as insulated from human interaction as they once were.

In recent decades, bats have been traced as the source of outbreaks of rabies, Marburg virus, NEPA virus, and Ebola.

To discuss why this is happening, I'm joined by Neil Vora.

He's a physician with Conservation International, a nonprofit environmentalist group, and he works on pandemic prevention.

Neil, thank you so much for joining us.

Tell me about what you and your colleagues have found out about human and bat interaction in recent years, in recent decades.

DR. NEIL VORA, Conservation International: It starts off with understanding about emerging infectious diseases.

We know that infectious diseases are increasingly emerging around the world since at least the 1940s, and most of these new infectious diseases originate in animals, then jump into people.

That's called spillover.

And spillovers are increasing around the world because of what we humans are doing to nature and how we're interacting with animals around the world.

Bats are getting stressed as we are disrupting their habitats and affecting their food supply.

We are stressing out bats in a variety of different ways, and that makes them more prone to illness and makes them more likely to shed viruses that can then go on to infect people.

Just like when we're stressed, we're more likely to get sick.

The same goes for bats.

ALI ROGIN: And why are bats so unique in their ability to carry viruses that can affect humans?

NEIL VORA: There's a variety of reasons for this.

One might have to do with different immune systems that bats have compared to humans, which allows them tolerate some viruses differently than humans can.

Furthermore, bats are able to fly over large distances, and so that allows them to carry viruses from one area to another, similar to how humans, if we're infected with a virus and we jump in a plane, we can carry that virus to other parts of the world.

So these are some of the factors that might explain why bats are able to transmit a number of viruses to humans but not be affected by them the same way we are.

ALI ROGIN: Tell us now about the vital role that bats serve in the ecosystem.

NEIL VORA: It's very important that we don't leave this conversation with the feeling that bats are bad, that we should be killing bats.

And bats are absolutely critical for pollinating plants and for controlling insect populations.

So, we should actually be doing what we can to preserve bat habitat and keeping a safe distance from bats and allowing them to live their lives while we go on to live our own lives and try to minimize the disruptions to bat habitats.

ALI ROGIN: And what are your policy recommendations for mitigating these risks to bats?

NEIL VORA: Number one, to reduce these spillovers, we need to be addressing deforestation.

Deforestation and other changes in habitats may be the single biggest driver of these spillovers of viruses from animals such as bats into people.

Number two is wildlife trade.

Both legal and illegal needs to be regulated and monitored more closely.

We've had a number of outbreaks associated with wildlife trade, such as MPOCs back in 2003.

Also the original SARS outbreak back in 2003 was also associated with wildlife trade.

And very likely the COVID pandemic was also related to the wildlife trade.

Number three is that we have to improve how we raise farmed animals.

We have to be doing that in safer conditions so that we can minimize the risk of animals that we are raising, such as cows and pigs, from getting infected with wildlife viruses.

ALI ROGIN: You mentioned COVID-19, and as you know, the origin has not been definitively linked.

There are two prevailing theories.

One, that it is the result of natural spillover.

The other, that it is linked to a laboratory in Wuhan, China, where the virus was originally detected.

And if we're talking about a multifaceted approach to mitigation, don't we also need to be looking at lab safety?

NEIL VORA: Absolutely.

We need to be looking at all the different places in which pathogens can arise and then start infecting people.

In the past century or past 105 years, we've had five other pandemics besides just COVID.

All five of those other pandemics, four food pandemics, and the fifth one I'm referring to is HIV.

All five of those were related to spillover events.

Now the 6th one that we just are emerging from COVID you're right, it's still up in the air as to the origins of the COVID pandemic, leading theories are that it's either spillover or a lab leak.

But most experts in the field actually are leaning towards the COVID pandemic, having started from a spillover event related to wet markets.

And so we have to be very clear about what the peer reviewed evidence shows.

But again, it's not conclusively been identified that COVID was started from a spillover event.

But I also want to make the point that even the very interesting to know how the COVID pandemic started, the bottom line is that we also know that we have to be taking actions to address spillover because the human actions for the environment and also improving laboratory safety.

ALI ROGIN: You mentioned the scientific consensus, so I just want to point out that the Biden administration maintains that both a natural and laboratory linked origin remain plausible hypothesis to explain the first human infection.

And both should be fully investigated.

And as we discussed, numerous viruses have been traced to newly deforested areas but Wuhan where the COVID-19 virus is not one of them.

So how do you explain that?

NEIL VORA: Well, I will explain that though the wildlife trading.

So, even though that area Wuhan might not have been recently deforested.

We also know that there are very (inaudible) wildlife markets within Wuhan and we might ever find out definitively what the cause of COVID was.

We still need to be taking actions to stop spillover and also be including laboratory safety and all of the above approach that's necessary.

ALI ROGIN: Certianly there is a lot that should be discussed with regard to the wildlife trade.

But as you know, the horseshoe bats that were being studied in the Wuhan China Institute of Virology originate 2,000 kilometers away from Wuhan in Yunan province.

So are you saying that these bats made it 2,000 kilometers without infecting anybody until they arrived in Wuhan?

NEIL VORA: Well, there might have been an intermediary animal in between.

So the virus might have originated from bats, jumped over into an intermediate animal and then jumped on into people.

And every time a virus passes from one species to the next, it actually can accumulate mutations that increase its pathogenicity, its virulence, meaning that the virus can become more infectious to people and more dangerous as well.

And so there's a lot of different possible pathways here.

But the bottom line is, again, that we know that there are certain high risk animals that pose public health threats.

So when they're sold in these markets, in urban settings, we have to be taking actions to improve the public health around that.

But I also want to be clear that we don't want to take away the rights of indigenous peoples and local communities from being able to access those wildlife species.

People certainly have a right to access them, but there's very little reason why wildlife needs to be sold in an urban market, because there's many other sources of protein that people in urban areas can be accessing.

ALI ROGIN: Neil Vora, a physician with Conservation International.

Thank you so much for joining us.

NEIL VORA: Thank you.