Coronavirus pandemic | How bats survive the lethal virus while humans get killed

Representative image: Reuters

Amid the novel coronavirus pandemic that has hit the world, studies are underway to find out its origin and transmission. However, many studies say that COVID-19 may eventually be traced back to bats.

After the virus broke out, Chinese researchers took samples from patients in Wuhan, the central city of 11 million people where the pandemic began in December 2019. They compared the genetic sequence of COVID-19 and found a 96 percent match with a coronavirus found in horseshoe bats in southwest China, NPR reported citing a study published in Nature.

Even the World Health Organization (WHO) has not ruled out this possibility that the pandemic originated from bats.

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Bats are mammals that have forelimbs adapted as wings; as such, they are the only mammals that are naturally capable of sustained flight.

So, why do so many viruses originate from bats?

Bats are said to be the perfect hosts for a lot of disease-causing viruses, which seem more likely to spread to people. According to the NPR report, there are more than 130 different kinds of viruses found in bats.

The reason why these viruses infect human beings is their lot of contact with bats. There are billions of bats and more than 1,300 different species living on every continent except Antarctica, the report suggested.

According to Rebekah Kading, who researches emerging infectious pathogens at Colorado State University, lots of viruses are found in bats because there are a lot of bats out there. They live in huge, crowded colonies together. Bats share living spaces in groups consisting of millions at time. The viruses can pass easily between them through close contact with one another, the report said.

Also, they have long lifespans relative to their size and can live for more than 30 years. This gives them a long time to be persistently infected with the virus and shed it into the environment, Kading was quoted as saying.

Now, the question is how these viruses transmit from bats to human beings. These viruses are shed through urine, feces and saliva of bats, said the report. For instance, outbreaks of Nipah virus in Bangladesh have been linked with date palm sap collected from trees that bats had licked or urinated on.

But, why are these lethal viruses not deadly for the bats?

Scientists theorise that it has something to do with their ability to fly. Bats are the world's only flying mammal. When they fly, their body temperature spikes to over 100 degrees Fahrenheit, said the report, adding that their heart rate can surge to more than 1,000 beats per minute.

For most land mammals, these are signals that would trigger death, but bats have developed special immune systems to deal with the stress of flying, the report stated quoting Linfa Wang, who studies bat viruses at Duke-NUS Medical School in Singapore.

Bodies of bats make molecules, which help repair cell damage. Also, their systems do not overreact to infections, which keeps them unaffected from the many viruses they carry, explained Wang.

This also signals that it is not always the virus itself but the body's response to the virus that can make human beings sick, Wang added.

What can be done to prevent future outbreaks of bat viruses?

It looks difficult to create vaccines and drugs for all the emerging viruses from bats. However, something that can be done is to identify factors that are making bats come into contact with humans and domestic animals and do something about it.