Narrator: Nipah, Hendra, Ebola, Marburg, SARS, these are some of the world's scariest viruses. Hemorrhagic fevers like Ebola are extremely fatal. They kill up to 90% of people infected. While SARS, a corona virus, has a lower mortality rate, but spreads incredibly rapidly. All of these nasty pathogens have surfaced in humans in just the last 50 years. And they are all carried by bats which, to be clear, really isn't bats' fault.
The reason rising outbreaks is likely due to humans and our animals creeping ever farther into bats' territory, especially in the tropics. In Malaysia, for example, the spread of commercial pig farms into bat-inhabited forest led to the first human outbreak via pigs of Nipah. And in Australia, human Hendra cases are cropping up as destruction of native forest forces fruits bats to feed in suburban gardens. But still, bats do appear to carry more human killing diseases than pretty much any other animal.
One big reason is that, with a few notable exceptions, bats love company. Different kinds of bats often roost together and huge numbers enclose quarters which helps viruses spread not just between individuals, but also between species. What's more, most infected bats don't die. They live pretty normal bat lives flapping around and giving the viruses time to spread. In fact, flight may be the reason bats are so resilient to infection.
As a rule, mammals can't produce the immense amounts of energy needed for flight without also producing a lot of reactive waste products that damage our DNA. So, when our bat cousins took to the air, they leveled up their in-flight DNA damage repair kits and other defenses including specialized cells that keep viral invaders in check, so bats can survive the deadly viruses. But what may matter even more, for humans anyway, is how the viruses survive the bats.
Nasty as they are, most viruses are also extremely finicky. In order to thrive, they require the perfectly controlled climate inside a normal, resting, on-the-ground mammal. But when bats take to the air, their internal temperatures cruise to around 40 degrees Celsius. Those frequent in-flight saunas are far too toasty for your average virus, but a few hardy viruses have evolved to tolerate the heat which, incidentally, means they can definitely weather a meager human fever.
Essentially, flight may have helped bats gain virtual immunity to viruses, and to train viruses to be virtually immune to us. Stupid flying. So what should we land-flappers do? We need bats for insect control and pollination and a whole bunch of other things. Maybe we could even learn some immune tricks from them, like how to be really good at not getting cancer. Plus, bats aren't the biggest carriers of human disease, humans are. Just do the math. Perhaps we'd be better off leaving bats alone, and trying to control the spread of diseases carried by a different kind of flying mammal.There may be small errors in this transcript.