Explained: What make the bat the deadliest disease carrier

Beijing, Feb 14: Ebola, Nipah, Marburg, SARS, MERS, and now the new coronavirus Covid-19, all share one thing in common - they are thought to have originated in bats.

Bats are potentially special in hosting numerous viruses that are extremely harmful when they infect humans and other animals.

So, what makes bat so special about it?

According to new research led by scientists at UC Berkeley, it's because bats may be the ultimate incubator, courtesy of a fierce effective immune system that seems to, in effect, train up viral strains, encouraging them to adapt and evolve into becoming as fit and infectious as they possibly can and when the viruses cross over into other animals or humans.

However, Bats do not react to infection with the typical inflammatory response that often leads to pathological damage.

On the other hand, in humans, while the inflammatory response helps fight infection when properly controlled, it has also been shown to contribute to the damage caused by infectious diseases, as well as to aging and age-related diseases when it goes into overdrive.

The researchers also found that the inflammation sensor that normally triggers the body's response to fight off stress and infection, a protein called NLRP3, barely reacts in bats compared to humans and mice, even in the presence of high viral loads.

This was found out when the researchers compared the responses of immune cells from bats, mice and humans to three different RNA viruses -- influenza A virus, MERS coronavirus, and Melaka virus.

The results showed that the inflammation mediated by NLRP3 was significantly reduced in bats compared to that of mice and humans.

This means that the bats instead of having the ability to fight with the infection, they rather have a much higher tolerance for it which actually enables them to survive.

But why do bats have such powerful immune systems?

Since, Bats being the world's only flying mammal, their intense physical activity increases their body temperature and metabolic rate, and puts their bodies into a constant state of 'fever'.

In gneral, fast metabolism and heart rate equals shorter lifespans of mammals while slower metabolism and heart rate results in longer lives.

Bats on the other hand, can live 30 or 40 years, despite having metabolic rates double that of rats.