Bats Act as Massive Reservoirs of Viruses

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Neucrad Health India April 15, 2020

Everyone is aware of the COVID-19 pandemic, which has affected more than 2,000,066 individuals and claimed over 126,754 lives until April 15, 2020 [2]. Consider the severe acute respiratory syndrome (SARS) outbreak in 2003, which resulted in 8098 infections and 774 deaths or the Middle East respiratory syndrome (MERS) epidemic claiming 492 lives in 2015 [3]. Let us take a look at the Ebola virus outbreak infecting over 28,616 cases in the West African region between 2014 to 2016 and 2018 Nipah virus outbreak in Kerala, resulting in the loss of 17 lives [4]. Do you find anything in common in all these epidemics? Yes, in all the above cases, bats played a crucial role in transmitting the virus to human beings.

Why did bats act as host in most of the epidemics in recent history?

All the outbreaks mentioned above were zoonotic, and bats were their primary host. Researchers feel that bats are currently one of the highest reservoirs of several groups of pathogens. Loss of habitat has made these furry flying mammalian species come in close contact with human beings. They store the viruses in their body and pass on to other animals whenever there is close contact between them. It led to a high possibility of transmission of these viruses to human beings causing severe epidemics.

A Close Look at these Furry flying mammals

Currently, Taxonomists have identified more than 1300 species of bats inhabiting the world. They belong to the Order Chiroptera, Suborder Yangochiroptera and Yinpterochiroptera, Family Pteropodidae and Rhinolophoidea. They are the second-largest group of mammals roaming in our planet. You can find them in a wide range of places except for cold polar regions and hot deserts. These animals are social and like to inhabit in a group of hundreds and thousands of members. They also play a crucial role in our ecosystem by dispersing seeds, pollinating flowers, and manifesting a vast diversity in their eating habits.

Unique Immune System of Bats

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Bats also possess a unique immune system making them a potent reservoir of several groups of viruses. They are highly active animals, continually flying in search of prey and new habitats. As a result, these mammals have a high body temperature and metabolic rate. It helps them to build up a strong immune system which “Flights as Fever”. Since their body temperature is constantly high, bats develop high resistance to viral infection, allowing them to act as symptom-less carriers. So, these animals may have a high viral load in their body, which they can successfully transmit to other animals without themselves getting infected.

High Interferon Levels of Bats also Help in Combatting Diseases

An eminent virologist Arinjay Banjeree and colleagues, recently pointed out that bats also have a high level of interferons (IFNs). Animals secrete these compound to fight against diseases. An analysis of bat cells revealed that their Type 1 IFNs is much higher than human beings, providing them with the ability to interfere with the viral replication and eliminating pathogens from the body. [7] A study on Big Brown Bats also pointed out that their cells have low levels of inflammatory cytokines. These cytokinin cells, guarded with other immune cells, rush to the infection spot to kill the pathogens before they spread to others. Since bats have reduced inflammatory cytokines, they pass on the infection to others quickly. [8]

This was a brief analysis of the life-style of bats, making them prone to transmitting infections to other organisms. However, we must also keep in mind that the invasion of their habitats by human beings also played a crucial role in the recent epidemics. Finally, we would like to say that human beings should maintain a controlled approach in encroaching animals’ habitat to limit future outbreaks.