Wildlife volunteers associated with the municipal corporation of Bengaluru in Karnataka are receiving a flurry of calls from citizens to clear bats from trees, even as leading conservationists call to seek an end to the “viral witch hunt” against bats in the Covid-19 pandemic.
“Whenever there are disease outbreaks we start receiving complaints on bats. This happened during the Nipah outbreak in 2018. In the present situation, because of the misconception on bats and Covid-19 linkages, we are receiving calls for removing bats from trees and also cutting trees,” R Sharath Babu, wildlife advisor to Bruhat Bengaluru Mahanagara Palike, told Mongabay-India.
To counter the misinformation, Sharath Babu said volunteers are sharing communication material in the local language with the complainants emphasising the important role bats play in ecosystems.
The complaints prompted the Karnataka Forest Department to issue a directive on April 22 against harming bats or their habitats and it said that if anyone is found killing or harming bats or destroying their habitats, necessary action will be taken in accordance with the applicable law.
Genetic analyses of SARS-CoV-2 – the virus causing Covid-19 – suggest that the virus likely originated from a bat reservoir. There are a number of theories regarding the presence of an intermediary animal host for the origins of SARS-CoV-2, but it has not yet been identified.
All animals have viruses that live inside them, and bats, as well as a range of other mammal groups, happen to be natural carriers of coronaviruses.
There are over 1,400 species of bats worldwide. Over a third of bat species assessed by the International Union for Conservation of Nature are considered threatened or data deficient, and well over half of the species have unknown or decreasing population trends. India has a diverse population of bats – at least 128 species of bats have been recorded, belonging to nine families and Meghalaya is home to about half of the recorded bat species in India, according to the Zoological Survey of India.
The shy, flying mammals have come under intense scrutiny following misleading interpretations of preliminary research linking bats as the most likely reservoir for SARS-CoV-2 as it is very similar to a bat coronavirus.
While scientists race to pinpoint the exact source and the transmission pathway of the novel coronavirus, oversimplification of scientific facts and misinterpretations have triggered a backlash against bats, prompting bat biologists and conservationists to clear the air on Covid-19 and bat-borne viruses.
“Not just India, this is happening in other parts of the world including in Switzerland. People are uncomfortable having bats around them. Even if a cat catches a bat and brings the bat to the house, people are panicking. There’s an overreaction because of the misinterpretation of scientific reports,” Manuel Ruedi, curator of the mammal collection in the Natural History Museum of Geneva, Switzerland, told Mongabay-India.
In a statement released on April 24, 64 chiropterologists from six South Asian nations debunked myths on Covid-19 and bats stating that bats do not spread the novel coronavirus disease. “The novel coronavirus diverged from the closest coronavirus found in bats called RaTG13, 40-70 years ago indicating that the bat virus cannot directly infect humans,” the statement, accessed by Mongabay-India, said.
Bats and ecology
Bats perform vital ecosystem services. In India, they pollinate the flowers of mangroves and create our strong coastal shield to natural barriers. They also act as pest controllers in rice and tea plantations, something that we are only beginning to understand, the researchers said in the statement.
“Human activities and encroaching upon wildlife habitats puts us at risk of encountering new viruses. These viruses may come from any wildlife species and not necessarily just bats. Thus, we need to modify human practices to prevent the emergence of new pathogens,” said Arinjay Banerjee, a postdoctoral researcher at McMaster University, Canada, who studies bat viruses and was part of the team that isolated the Covid-19 virus, in the statement.
The researchers urge people to not believe news from unverified sources and cause harm to bats in retaliation. “Likewise, we request the media to not oversimplify scientific evidence, to emphasise the role of humans in disease outbreaks, and to highlight the importance of coexistence with bats in urban landscapes.”
The group of researchers stressed on strengthening the protection for bats. “In India, only two species [out of 128] are protected by law, while many other species are more endangered or lack scientific information. In Nepal, too, all 30 species are unprotected, including two species from the National Red List and the same is true for Pakistan. We urge the governments of these countries to reconsider and reinforce the laws governing bat conservation. ”
Understanding spillovers
Conservationists argue that incorrect interpretation of scientific facts may impede important conservation efforts needed to preserve bats and their fragile ecosystems. Manuel Ruedi who has been studying bats from Europe and Southeast Asia, said the demonisation of the animal group may undo the important efforts in outreach on the significance of bats in ecosystems.
“It took several decades in Europe to change the idea and inform people that bats are really beneficial for humans in many ways – feeding on pests for instance. The more information people have the better they understand that spillover is different from just having a bat in the house. The widespread misinformation does harm to all the efforts we made in informing people,” pointed out Ruedi.
Bats can carry viruses that are deadly to other mammals without themselves showing serious symptoms and they have a suite of antiviral defenses that keep the amount of virus in check, scientists have said.
Scientists at the Indian Council of Medical Research’s National Institute of Virology who detected the presence of pathogenic bat coronaviruses in two species of Indian bats in a screening study published in April to understand the coronavirus circulation in them also underscored that these reported coronaviruses are “far different” from SARS-CoV-2.
“Coronaviruses are reported from several vertebrate species and they are normally very host-specific. Similarly, several bat coronaviruses have been reported from various parts of the world,” said study author Pragya Yadav, of National Institute of Virology’s Maximum Containment Laboratory.
“The bat coronaviruses we reported are far different from SARS CoV-2 and there is no association of Covid-19 from bats in India in the present context,” Yadav told Mongabay-India.
The study authors, however, underscored the need for enhanced screening for novel viruses in Indian bats, calling for the “One Health” approach with collaborative activities by the animal health and human health sectors in these surveillance activities shall be of use to public health.
This would help in the development of diagnostic assays for novel viruses with outbreak potential and be useful in disease interventions. Proactive surveillance remains crucial for identifying the emerging novel viruses with epidemic potential and measures for risk mitigation, they write in the study.
The research emphasis on bats makes a lot of practical sense because bats are hosts of numerous medically significant viruses – Ebola virus, rabies virus, Nipah virus, Hendra virus, among others – notes Barbara Han, disease ecologist at the Cary Institute of Ecosystem Studies.
“These pathogens cause zoonoses with high case fatality rates in humans, and some of these zoonoses do not have countermeasures. So understanding what drives the spillover of bat-borne viruses is, therefore, an easily justifiable research area. However, there does appear to be disproportionate villainisation of bats compared to other animal groups,” Han told Mongabay-India.
Fact check
There is clear evidence linking bat-borne viruses to numerous human diseases, but Han thinks making generalisations about the risk of bat-borne coronaviruses in humans is “premature.” Many species carry coronaviruses, which naturally circulate in many vertebrates, she says.
But in general, the number of viruses in any animal group – bats, rodents, carnivores or primates – scales with the number of species in a group. This means that groups with more species will also have more viruses.
“The number of viruses in bats and rodents [that have over 2,200 species] is expected to be proportionally greater than viruses found in, for example, primates or carnivores, which each have less than 300 species and are therefore likely to have fewer viruses. The number of zoonotic viruses seems also to follow this same pattern,” said Han.
Han said the high number of coronaviruses observed from bats is not that surprising. “Bats have a high species diversity. In addition to this, they have been sampled more intensively for viruses than perhaps any other group.”
A recent study published in PNAS suggests the number of zoonotic viruses linked to each animal order appeared to be a consequence of species richness: more diverse animal orders hosted more viruses in general and by extension, more zoonotic viruses.
These findings suggest previous scientific thinking – that certain animal reservoirs, such as bats, pose a heightened risk of spreading viruses to humans – may not be accurate. This means that ongoing efforts to identify potential future threats to human health by screening animals for undiscovered viruses will need to focus on a much wider range species than is currently the case.
A ‘witch hunt’
Veteran bat conservationist Merlin Tuttle observed there are more than 1,400 species of bats spread throughout the world and so we would expect them to have a wide variety of viruses but it is yet to be documented that bats are any more dangerous than other animals.
Writing in the Journal of Bat Research and Conservation, Tuttle says that “historically, the world’s greatest zoonotic pandemics have not come from bats. Currently, H7N9 bird influenza, and drug-resistant microbes, pose significant threats but are gaining far less research or media attention. It is time to focus more on known threats, and less on speculation about possibilities not yet verified.”
“In fact, they [bats] have one of our planet’s best records for not spreading diseases. We still don’t even know if bats actually have more viruses than other animals. They have been far better searched. New viruses can be discovered wherever we look, even on our own bodies. Huge numbers have yet to be identified,” Tuttle told Mongabay-India.
The vast majority of viruses are either innocuous or beneficial. However, when a new virus is found in a bat, it’s automatically speculated to be potentially dangerous, he rued.
According to a World Health Organisation situation report, another coronavirus, SARS-CoV-1, the cause of the Severe Acute Respiratory Syndrome outbreak in 2003, was also closely related to other coronaviruses isolated from bats. These close genetic relations of SARS-CoV-1, SARSCoV-2 and other coronaviruses, suggest that they all have their ecological origin in bat populations.”
“The big problem is that since it was concluded that SARS came from bats, which hasn’t yet been actually proven, there has been a huge focus on bats, and whenever there is concern about a new virus, it is mostly looked for in bats; this has turned into a viral witch hunt,” Tuttle said. He added that we are looking almost exclusively in bats for many of these things and of course, we are going to find more viruses in the animals we most often search.
Tuttle also elaborated on the sampling bias. Bats are by far the easiest mammals to sample quickly.
“When Covid[-19] first broke out, some of the early speculations were that it even came from cobras. Can you imagine being told that you have to sample 30 cobras? 30 bats would be so much easier and safer. Virologists get quick publications easily from bats and bats have few defenders and it is easy to scare people with bats because we fear most what we understand least. The marriage between bats and viruses seems to provide the perfect storm for scaring people,” he said.
Even Ebola, which has been widely attributed to bats and intensely searched for in them, has not been confirmed from bats. “Bats still get the primary blame, even for MERS, despite clear documentation that human cases originate in camels who are ideal reservoirs. In case after case, so-called virus hunters have prematurely speculated bat origins, then attempted to prove rather than test this hypothesis. Such biases delay much-needed progress,” said Tuttle.
Manuel Ruedi said having a catalog of viruses in bats is fine but you need to research how it passed into humans in the spillover. “We did find an Ebola-like virus in one species of bat [fruit bat in Africa]. It’s the closest we have found so far, but not identical to the one infecting humans. We do have a scenario but that is not the bat itself. It’s a whole series of events that led to a spillover of infection,” Ruedi said.
Coexisting with bats
The experts also underscored the long history of co-association of bats and humans. “We have a long history of co-association, in caves, thatched huts, and log cabins,” said Tuttle. “Millions of humans in Africa, Asia, and the Pacific and Indian Ocean Islands still eat bats. Thousands of inhabitants of the Old-World tropics spend countless hours in bat caves collecting guano for fertilizer. Thousands of sport cavers explore caves worldwide. Millions of Africans share their cities with huge bat colonies, all without detected disease outbreaks.”
Referring to the bat harvests and consumption of the animals in remote Northeastern regions in India, Ruedi, who also works on the group in Northeast India, said, “If you consider rabies, it is a major issue over the years. 20,000 of an estimated global annual 55,000 rabies deaths occur in India because they are bitten by stray dogs. This is much more an issue than a spillover that didn’t occur in thousands of years in India.”
Ruedi co-authored an inventory with Zoological Survey of India’s Uttam Saikia, titled The Bat Fauna of Meghalaya, Northeast India: Diversity and Conservation, which discusses the diversity of bats in Meghalaya and the conservation challenges, including indiscriminate mining.
They also communicated to the community the “role of bats in their environment, and how important they are to help control pest insects and also that they should not only be viewed as potential proteins to eat but also creatures of God worth protecting.”
Their communication efforts encouraged the community in the village of Pynurkba in East Jaintia hills to dedicate a small patch of their forest to save the rare Wroughton’s free-tailed bats. “It took us almost one year to convince the village elders to declare the area as a community reserve. It is a 2.4-hectare patch and surrounds the cave. The area is now notified as a community conservation reserve,” said H Lato, divisional forest officer of Jaintia Hills.
This article first appeared on Mongabay.
