T he human race has experienced some of the most deadly pandemics in recent centuries. A good number of these diseases hoped across species, notably bats. Ebola that ravaged West Africa in last years and the Nipah virus in Asia, as well as the new coronavirus that erupted in late 2019, appears to have come from bats.
It is believed that bats host more than 60 human infecting viruses that are yet to be identified. But the main question among the science community is how do they manage to carry so many deadly viruses without being affected?
According to a new study by the University of California in Berkeley, the bats’ ferocious immune response to viruses could have something to do with the viruses replicating faster in their bodies; thus when these viruses hop to mammals with the regular immune system, like humans, they cause severe damages.
Bats have been found to possess immune systems that are always primed to mount strong defenses against all sorts of viruses. In case of any infection from a virus, the immune system of the bat responds by eliminating the virus out of its cells. This encourages the viruses to replicate more quickly in the bats before any defense can be mounted.
Because of this, bats have evolved to become a unique reservoir of speedily replicating and highly contagious viruses. But because humans or mammals don’t have a fast-response immune system, the viruses can quickly overwhelm their defense system, resulting in high fatality rates.
Why don’t these deadly viruses kill the bats?
Scientists believe that the reason could affect the ability of bats to fly. Flying uses a lot of energy, and when the body generates this power, a lot of waste is produced. Due to the bats’ sophisticated immune system, this reactive waster cannot damage their DNA.
Bats have very few predators, and as a result, they can live for a long time in relation to their size. Some species of bats can live up to 40 years.
This ability to live long, coupled with the bats’ rapid tapping down of inflammation, may also have another effect on their ability to live with so many viruses.
Bats are the natural reservoir for Nipah and Hendra viruses and Marburg virus, which have wreak havoc in humans, especially in Africa, Malaysia, Australia, and Bangladesh. They are also believed to the natural reservoir for the Ebola virus as well as rabies viruses, though they are affected by the later.
Their virus tolerance outshines that of other animals, including humans, and this is one of their most powerful traits. Bats are the only flying mammals, can feast of disease-carrying insects, and are mostly in the pollination of lots of fruits such as avocados, bananas, and mangoes.
According to a study performed by scientists in Singapore and China about how bats handle their DNA sensing, they found that flight plays a crucial role in how these mammals deal with a large number of viruses in their bodies.
They found that the energy required for flight is so immense that the bat’s body breakdown and releases small amounts of DNA that float around in areas where they are not supposed to be. Biologically, mammals have a mechanism to identify and respond to these bits of DNA, which usually indicates an invasion of an infectious organism. However, in bats, researchers have found that evolution has weakened that natural system, which typically causes inflammation as t fought the disease-causing viruses.
For this reason, bats have lost some essential genes involved in response to these bits of DNA, which explains why even the inflammation doesn’t affect them. According to scientists, this weakened response that allows bats to maintain a balanced state of effective response against the many viruses they host.
Currently, scientists are trying to find ways to contain the 2019-nCOV, and no one is paying significant attention to its origin. However, tracing where the virus originated from may help prevent future outbreaks, and this depends on sufficient insights and monitoring of bats.
Before the outbreak of the 2019-nCOV, researchers in China were already studying bats and were aware another pandemic was already on the horizon.
In an article published by a group of Chinese researchers last year (2019), on bat coronaviruses, “it is generally believed that bat-borne CoVs will re-emerge to cause the next disease outbreak,” adding that “In this regard; China is a likely hot spot.”
Bats live in all corners of the earth except Antarctica and are close to human settlements and farms. Their ability to fly means they can reach any region, thus spreading the viruses quickly. Moreover, their droppings can also spread illnesses.
Communities in some regions eat sell and eat bats. Previous coronaviruses, including the SARS, originated from bats in an animal market, and so the latest coronavirus that is sending fear across the globe, which began in an animal market in Wuhan. Bats also tend to live in large colonies, which is an ideal environment for the viruses to hop from one animal to another.
However, bats should not be blamed for the current outbreak of coronavirus. It is essential to point out that its humans who have encroached on the bats’ lives and not the other way round.
In live animal markets, animals that would otherwise not have naturally mixed come together. For instance, a bat in a crate could be stacked over a chicken, which in turn combines with humans.
So, for humans to prevent themselves from future pandemics, it is vital to continuing studying bats.