Night began to fall in Rio de Janeiro’s Pedra Branca state park as four Brazilian scientists switched on their flashlights to traipse along a narrow trail of mud through dense rainforest. The researchers were on a mission: capture bats and help prevent the next global pandemic.
A couple of metres ahead, almost invisible in the darkness, a bat made high-pitched squeaks as it strained its wings against the thin nylon net that had ensnared it. One of the crucial researchers removed the bat, which used its pointed teeth to bite her gloved fingers.
The November middle of the night outing used to be a part of a project at Brazil’s state-run Fiocruz Institute to gather and study viruses present in wild animals — including bats, which many scientists consider were linked to the outbreak of Covid-19.
The goal now is to identify other viruses that can be highly contagious and deadly in humans, and to use that information to devise plans to stop them from ever infecting people — to forestall the next potential global disease outbreak before it gets started.
In a highly connected world, an outbreak in one place endangers all the globe, just as the coronavirus did. And the Brazilian team is just one in every of many worldwide racing to reduce the risk of a second pandemic this century.
It’s no coincidence that many disease scientists are focusing attention on bats, the the world’s only flying mammals. Bats are considered the original or middleman hosts for a couple of viruses that have spawned recent epidemics, including SARS, MERS, Ebola, Nipah virus, Hendra virus and Marburg virus.
A 2019 study found that of viruses originating from the five most common mammalian sources — primates, rodents, carnivores, ungulates and bats — those from bats are the most virulent in humans.
Bats are a diverse group, with more than 1,400 species flitting across each and every continent apart from Antarctica. But what many have in common are adaptations that allow them to carry viruses that are lethal in humans and livestock while exhibiting minimal symptoms themselves — meaning they’re in a position commute and shed those viruses, instead of being quickly hobbled.
“The name of the game is that bats have abnormal immune systems, and that’s related to their ability to fly,” said Raina Plowright, an epidemiologist who studies bats at Montana State University.
Plowright and other bat scientists consider evolutionary tweaks that help bats recuperate from the stress of flying, when their metabolic rate rises sixteen-fold, also give them additional protection against pathogens.
Probing the secrets of bat immune systems may help scientists understand more approximately when bats do shed viruses, in addition to providing hints for conceivable future medical remedy strategies, said Arinjay Banerjee, a virologist at McMaster University in Canada.
Increasing destruction and fragmentation of habitats worldwide — particularly biodiverse areas like tropical forests — means “we are seeing higher rates of contact between wildlife and humans, creating more opportunities for spillover,” said Cara Brook, a disease ecologist at the University of California, Berkeley.
In India, a National Mission on Biodiversity and Human Polite-Being has been pending since 2018 and will likely be launched next year. A core a part of the plan is to establish 25 virus surveillance sites across the country.
A varied patchwork of virus surveillance programs exists in several other countries, but underwriting has a tendency to wax and wane with the political climate and sense of urgency.
One approach that won’t help, scientists say, is treating bats as the enemy — vilifying them, throwing stones or trying to burn them out of caves. An attack along those lines took place this spring, when villagers in the Indian state of Rajasthan identified bat colonies in deserted forts and palaces and killed hundreds with bats and sticks.
Scientists say such tactics are likely to backfire.
“Stress is a large factor in upsetting the natural balance that bats have with their viruses — the more you stress bats, the more they shed viruses,” said Vikram Misra, a virologist at the University of Saskatchewan in Canada.
“People have a large number of misconceptions approximately bats. They’re nocturnal and look a little bizarre flying,” said Hannah Kim Frank, a biologist at Tulane University. “But bats aren’t aggressive — and attacking bats doesn’t help keep watch over diseases.”
Bats also play imperative roles in ecosystems: They consume insects like mosquitos, pollinate plants like agave, and disperse seeds.
“We in fact need bats in the wild to consume insects that another way destroy cotton, corn and pecan harvests,” said Kristen Lear, an ecologist at Bat Conservational International.
A better approach to reduce disease risk, Frank said, is simply to reduce contact between wild bats and people and livestock.
In Australia, widespread destruction of winter flowering eucalyptus trees that supply nectar for fruit bats — known in the community as “flying foxes” — prompted the bats to move into areas closer to human settlements searching for alternate meals, including to a suburb of Brisbane called Hendra.
There, the bats transmitted a virus to horses, which in turn infected people. First identified in 1994 and named Hendra virus, it is highly deadly, killing 60% of people and 75% of horses infected.
To potentially reverse the movement of bats, Montana State University’s Plowright and colleagues based in Australia are studying restoring the bats’ original habitat.
“The idea is to plant new forests and ensure they’re absent from places with domestic animals and people,” she said.
Bats aren’t the problem, said Ricardo Moratelli, coordinator of the Fiocruz project in Brazil. “The problem is when human beings enter into contact with them,” he said.
(This story has been published from a wire agency feed without modifications to the text.)
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