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Posted On: 11 March 2020 04:13 pm
Updated On: 12 November 2020 09:10 am

Are these coronaviruses all coming from bats?

Khadiza Begum
Khadiza Begum
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CORONAVIRUS – this may be the most talked-about issue currently worldwide! The virus has spread across the globe and has infected more than 113,000 people globally and killed over 4,000, according to CNN's tally as of March 10, 2020. With movement restricted, events canceled, schools shut - a lot of countries are having a harder time coping with the dramatic coronavirus crackdown.

Have you ever wondered what the source of this virus is? Researchers say that it's no coincidence that some of the worst viral disease outbreaks in recent years like SARS, MERS, Ebola, Marburg and likely the newly arrived 2019-nCoV virus -- appear to have originated in bats. Sounds interesting or weird? How come these viruses originate from bats and spill over to humans! Let’s scroll all the way down and know more about this!

Coronaviruses

According to the World Health Organization, Coronaviruses (CoV) are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV). A novel coronavirus (nCoV) is a new strain that has not been previously identified in humans.

Coronaviruses are zoonotic, meaning they are transmitted between animals and people. Detailed investigations found that SARS-CoV was transmitted from civet cats to humans and MERS-CoV from dromedary camels to humans. The origins of the virus are not fully understood but, according to the analysis of different virus genomes, it is believed that it may have originated in bats and was transmitted to camels sometime in the distant past.

Bats – the natural reservoir for many viruses!

One bat can host many different viruses without getting sick. They are thought to be the natural reservoir for many viruses. According to a research study “Coronavirus outbreak raises questions: Why are bat viruses so deadly?” some bats have been shown to host immune systems that are perpetually primed to mount defenses against viruses. Viral infection in these bats leads to a swift response that walls the virus out of cells. While this may protect the bats from getting infected with high viral loads, it encourages these viruses to reproduce more quickly within a host before a defense can be mounted. This makes bats a unique reservoir of rapidly reproducing and highly transmissible viruses. While the bats can tolerate viruses like these, when these bat viruses then move into animals that lack a fast-response immune system, the viruses quickly overwhelm their new hosts, leading to high fatality rates.

In a 2017 report in Nature, Dr. Daszak, Kevin J. Olival and other colleagues from EcoHealth Alliance, reported that they had created a database of 754 mammal species and 586 viral species, and analyzed which viruses were harbored by which mammals and how they affected their hosts.

They confirmed what scientists had thought: “Bats are host to a significantly higher proportion of zoonoses than all other mammalian orders.” Zoonoses are diseases that spill over from animals to humans.

So how do they spread viruses?

Bats live on every continent except Antarctica, in proximity to humans and farms. The ability to fly makes them wide-ranging, which helps in spreading viruses, and their feces can spread disease.

Bats are unique among mammals in their ability to fly. Bats fly daily in pursuit of food, and bats of many species fly long distances during seasonal migrations.

And they don’t just survive the viruses they harbor. Bats are remarkably long-lived for small mammals. The big brown bat, a common species in the United States, can live nearly 20 years in the wild. Others live closer to 40. One tiny bat in Siberia lived at least 41 years. Animals like house mice live about two years on average.

People in many parts of the world eat bats, and sell them in live animal markets - the seafood market in Wuhan, capital of Hubei province is of the examples, which scientists have suggested as a possible source of the virus.

China's wet market tradition makes it susceptible to disease spread.
(Wet market tradition is suspected for coronavirus disease spreading. Photo credit: Anthony Kwan —Getty images)

Bats are traditionally eaten in the form of a curry or soup. Recently, some unconfirmed footage emerged on social media show how the bat soups are consumed from a bowl with a grinning dead bat on the side. However, there is no official confirmation that bat soup can be a reason behind coronavirus.

The bottom-line

How to manage and contain the current outbreak of the virus officially known as 2019-nCoV, is, of course, of paramount importance now. But tracing its origin and taking action to combat further outbreaks may depend partly on knowledge and monitoring of bats. “The outbreak can be contained and controlled,” Dr. Daszak said. “But if we don’t know the origin in the long term then this virus can continue to spill over.”

Dr. Daszak stressed that stopping the sale of wildlife in markets is essential to curtail future outbreaks. But since such outbreaks are inevitable, Dr. Daszak says, monitoring and studying wildlife, like bats, is equally important. To get a jump on them, he said, intelligence is vital.