Field Notes Society

Get bats out of hell: Bats are one of the most misunderstood mammals

Fying foxes in Chennai’s Egmore Museum grounds.   | Photo Credit: S. Thanthoni

In April, in the midst of the pandemic, actor Amitabh Bachchan tweeted about a bat that had entered his house; he also drew a link between the creature and the novel coronavirus. The post attracted a fair share of rebuke from people who said it was irresponsible coming from someone with such a large following.

Not vermin

Bats, creatures of the night that we once took for granted, have suddenly emerged as villains after some scientists said a bat in China was found to have a pathogen similar to the novel coronavirus. However, the exact source of the virus has not yet been identified. “The closest match of the novel coronavirus was found in one out of 1,400 species of bats,” points out Rohit Chakravarty, bat biologist and Ph.D student at Leibniz Institute for Zoo and Wildlife Research, Berlin. And, he says, the bat coronavirus does not infect humans directly, because viruses have a receptor binding site that binds to the cell that it is going to affect, which in COVID-19 is the lungs. “The bat coronavirus does not have the right receptors to bind to our lungs, which further brings scientists to the conclusion that there has to have been an intermediate host.”

None of this has made any difference to frightened and ignorant humans. Reports of trees with bats being destroyed have come

A painted bat found near Kancheepuram

A painted bat found near Kancheepuram   | Photo Credit: B. Jothi Ramalingam

from Rajasthan, Mysuru, etc., and people have called for the destruction of their habitats in cities such as Bengaluru, where civic bodies and citizens have intervened. Chief Wildlife Warden Sanjay Mohan had to issue a warning last month that anyone found harming bats would be prosecuted. These moves to eliminate bats have seen a sharp spike, agrees Rajesh Puttaswamaiah, Citizen Scientist and Trustee, Bat Conservation India Trust. “It is high time all bat species are brought under the Wildlife Protection Act, 1972 and fruit bats removed from the ‘vermin’ list.” In fact, Puttaswamaiah points out that bats are one of the most important mammals in the ecosystem. “Unfortunately, they are also the most misunderstood, with myths surrounding them. It’s important for people to know their role as pollinators, seed dispersers and pest controllers,” he says.

Bad rep

The reason bats have a bad reputation might be due more to fiction than fact. And due even more to media, social media and scientists. “Scientists interact with the media and their explanations tend to get oversimplified,” points out Chakravarty. The fact is, “all animals carry viruses,” he says. And while it’s true that bats make very good reservoir hosts, in most cases it requires

A rescued fruit bat in Matunga

A rescued fruit bat in Matunga   | Photo Credit: Prashant Nakwe

direct contact between humans and bats for the viruses to be transmitted, and this is very rare. What usually happens is that viruses spread through an intermediate host, explains the bat biologist. And this happens when there is habitat fragmentation and livestock farming on industrial scales, which create environments where bat viruses can jump to other animals and from them to humans. Zoonotic diseases spread either through direct transmission (for instance, rabies, SARS, and Ebola), or through a vector intermediary (Zika, Lyme disease, and Kyasanur forest disease).

Typically, regions with a high diversity of potential host species such as bats, rodents, primates and vectors also host the highest diversity of pathogens, explains Abi Tamim Vanak, convenor for the Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment. “But this by itself does not necessarily increase the risk of emergence of new pathogens,” says Vanak. “Only when it is combined with high densities of humans and livestock, and where environmental degradation is also high, does the risk of pathogen spillover increase.

Several researchers have shown that areas in Asia, particularly the Indian subcontinent, Southeast Asia and south China, are hotspots for the risk of emergence and re-emergence of infectious diseases.”

Leave them alone

Vanak quotes a recent paper that shows bats and rodents are no more likely to be reservoirs of zoonotic pathogens than any other group of animals, but the reason bats and rodents harbour more viruses is simply because these groups also have the most number of species. Are we really seeing new pathogens ‘emerging’ at a faster rate? Yes, but this could be because of better surveillance and healthcare systems resulting in higher rates of discovery, says Vanak. And if they are spreading rapidly across the world, that is “due to urbanisation, globalisation and an economic system that perversely incentivises the destruction of natural ecosystems for short-term gain.”

Rather than fear bats, the solution is not to disturb their habitats. “Studies show that destroying habitats leads to diseases,” says Neha Sinha of the Bombay Natural History Society. “For example, Lyme disease is related to deforestation in North America. Malaria is also linked to deforestation. We should let the animals be. Displacing them creates larger problems.” With climate change, there is increased speculation of new viruses and diseases. “Dengue has moved from tropical to temperate climates. Malaria has increased its range across the world. Viruses have been found in permafrost. It is prudent not to disturb ecosystems further by killing bats, but to take an evidence-based approach,” says Sinha. One hypothesis suggests, Vanak warns, that displacing bat colonies or reducing population sizes can actually increase the risk of viruses such as coronaviruses, filoviruses and the Nipah virus spilling over into humans.

If there’s any precaution humans can take, it would be to avoid direct contact with animal faeces and avoid eating fallen fruits or those with bite marks. And if you come across dead or injured bats, call professional rehabilitators or wildlife experts.

deepika.kc@thehindu.co.in

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Printable version | May 11, 2021 9:09:02 AM | https://www.thehindu.com/society/get-bats-out-of-hell-bats-are-one-of-the-most-misunderstood-mammals/article31702110.ece

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