Why do bats carry so many viruses?

Bats are the source of most zoonotic diseases that can infect humans. Nipah, SARS, Ebola, Marburg, the recent novel coronavirus outbreak…All originated from them. But why bats?. A new study by the University of California finds bats have a strong immune system. Bats, the only flying mammal, have high metabolism — they use a lot of energy. This can lead to an accumulation of free radicals, a reactive molecule that can damage tissues. To prevent this reactive waste from damaging, bats have evolved sophisticated defence mechanisms. This also helps the bats to defend themselves from deadly viruses and diseases. During a virus attack, bats produce a molecule called interferon-alpha. Which signals other cells to scale up their defence mechanism. To overcome this defence, virus starts to reproduce quickly and highly transmissible. Although the bats can tolerate these viruses, it can be deadly to other mammals like humans. Unlike bats, humans lack a fast-response immune system and the viral load becomes deadly. Disturbing the natural habitat of bats can stress the animals and shed even more virus in their saliva, urine and faeces, researchers said