The world’s bat lands are under attack, seeding risk of a new pandemic. Here’s where.

Indian flying foxes or fruit bats rest on tree branches inside a temple complex at Kadambazhipuram village in Palakkad district in the southern state of Kerala, India, February 3, 2022. (Reuters/Sivaram V)

This story is part of a series, “The Bat Lands.

FOMENA, Ghana — They take flight by the thousands, black clouds of fruit bats flapping above the forest as the last light leaves the sky. Hungry multitudes descend upon fruit trees here and around nearby towns, where forest has been cleared for farms, mines, houses and roads.

Beneath them, on paths and fields trod each morning by farmers and other settlers, the nocturnal foragers leave trails of bodily waste potentially bearing bat viruses: feces, urine and partially eaten, saliva-tainted fruit. Residents at times feed the bats’ leftovers to livestock. Sometimes, after cutting away bite marks, they even eat the fruit themselves.

This collision – bats and humans competing for resources on territory long the domain of the bats – could trigger the next pandemic.

Last June, a 26-year-old farmer here named Mahama Faatey died of a mysterious illness after three days of high fever and bleeding from his abdomen, mouth and nose. Lab tests confirmed he had Marburg: a deadly virus found in the Egyptian rousette, a common African fruit bat. Faatey’s infant son died of Marburg soon after. Their deaths came out of the blue: This was Marburg’s first known appearance in Ghana.

But a Reuters data analysis has found that the area where the farmer lived and worked was among the likeliest places on Earth for such an outbreak. As people destroy bat habitats worldwide, they are unwittingly helping bat-borne viruses mutate, multiply, and infect other species, including homo sapiens.

For millennia, bat viruses lurked across the forests of West Africa and in other undisturbed parts of the world but posed little threat to humanity. No longer, Reuters found. Today, these pathogens represent an epidemiological minefield in 113 countries and on every continent except Antarctica.

The danger posed by bats comes not through biting people, as portrayed in literature and cinema. Even the famed vampire bat rarely attacks humans. Bats, rather, scatter viruses in their saliva, urine, blood and excrement. Those viruses can then enter humans through direct contact or via other animals hosts.

What’s more, scientists say, the catalyst for outbreak isn’t bat behavior, but our own. Unchecked development of wild areas is amplifying the risk of global pandemics through greater contact with animals.

“People need to wake up to the fact that we’ve developed a very dangerous relationship with nature,” said Jonathan Epstein, a veterinarian and disease ecologist at EcoHealth Alliance, a U.S.-based global health research organization. As people encroach further into once-remote habitats, “that increases opportunity for viruses that used to be safely tucked away in the forest to now make their way into domestic animal and human populations.”

Intruding into the world’s bat lands gives rise to special perils. Bats are a leading reservoir of viruses: 72,000 by some estimates. Scientists don’t fully understand why that’s so, but they point out bats’ virus-packing superpowers.

Bats are exceptional incubators: They can harbor and survive viruses that kill other mammals. They’re potent proliferators: Some roost tightly together and in close quarters with other bat species. That means their viruses can rapidly spread and evolve – some equipped to infect other animals, such as people. And bats are prime delivery vehicles: Some can fly hundreds of kilometers in search of food – carrying viruses far and wide.

Scientists have yet to determine the source of the virus that causes COVID-19, the deadliest pandemic to emerge this century: Did it jump to humans from a wild animal, or leak from a lab? But of this they’re certain: It is related to coronaviruses found in some horseshoe bats, a type common in tropical Asia.

Even before hospitals and funeral homes were overrun with victims of that new pathogen, other viruses linked to bats had caused some of the deadliest new diseases of the last half century.

Ebola, Marburg, SARS, Hendra and Nipah together have struck more than 90 times, sickening about 44,000 people and killing more than 16,000. COVID-19 has killed nearly 7 million, according to the official tally by the World Health Organization, but senior officials at the global agency say the toll is certainly far higher because of the high number of unreported infections.

These viruses may jump from bats to humans either by way of an intermediary host, such as a pig, chimpanzee or civet, or more directly through human contact with bat urine, feces, blood or saliva. Such leaps are known as “zoonotic spillover.”

To examine where the next pandemic may emerge, Reuters used two decades of disease-outbreak and environmental data to identify places most vulnerable to spillover of bat viruses. The analysis revealed a global economic system battling nature and putting more than 1 billion people at risk, as bat-rich forests are cleared to make way for agriculture, extractive industries, infrastructure and other development.

Reuters is the first to conduct a global analysis that combines ecological factors to predict places where spillover of bat viruses has become more likely from year to year.

Reporters divided nearly the entire land surface of Earth into sectors, most of them roughly 25 sq km each. Then, the news agency used a computer model to score and rank each sector according to how similar the area’s conditions are to those that existed in 95 locations where bat viruses infected people between 2002 and 2020. Each locale was given a “similarity score.”

The analysis considered 56 factors that studies have linked to spillover, including tree loss, temperature, precipitation, livestock and the count of bat species in the area. In all, the analysis included nearly 8 billion such data points, many derived from satellites.

Next, with guidance from statisticians and scientists, reporters identified sectors most conducive to spillover. These areas ranked in the top 5% of the model’s similarity scores. By that measure, Reuters found more than 9 million sq km on Earth where conditions in 2020 were ripe for a bat-borne virus to spill over, possibly sparking another pandemic.

These areas, which we’ve dubbed “jump zones,” cover 6% of Earth’s land mass. They are mostly tropical locales rich in bats and undergoing rapid urbanization. Nearly 1.8 billion people lived in these jump zones in 2020, an increase of 57% since 2002. That means more than one of every five people on the planet is now living in areas where the risk is highest for spillover.

Not only are more people living in these places; they also are living closer together, increasing the chances for diseases to spread. Population density in jump zones soared by nearly 40% from 2002 to 2020. Most troubling, population is growing fastest and density increasing most in areas where conditions are ripest for spillover.

“The more people you have in a high-risk area, the more likely it is that a spillover happens,” said Hernan Caceres-Escobar, a scientist who studied emerging infectious diseases for the International Union for Conservation of Nature, a Geneva-based organization that assesses threats to species worldwide. “In an increasingly connected world, it is also more likely that a spillover will become an epidemic or a pandemic.”

Along with West Africa, the jump-zone analysis found growing spillover risk in locales including:

  • China, where COVID-19 surfaced, and neighboring Laos, where scientists have identified the closest relatives in wildlife to the virus responsible for the current pandemic;
  • India, where nearly half a billion people live in fast-expanding jump zones, the most of any nation;
  • Brazil, which has the most land at risk of any country, as humans ravage the Amazon.

It’s impossible, though, to predict exactly where a new spillover may occur.

No model, including the Reuters analysis, can capture all variables that could contribute to overall pandemic probability, such as undocumented illegal wildlife trade or a person’s consumption of an infected animal. Also immeasurable are some big forces, such as the risk that arises when bats are stressed by habitat disruption and global warming. Scientists have found evidence that such stress makes bats more prone to catch viruses and shed them through their bodily waste.

“You can’t pinpoint risk – this pathogen and this location and this time,” said Barbara Han, a disease ecologist at the Cary Institute of Ecosystem Studies in New York, of Reuters’ data analysis. “But what you can do – and what you are doing here – is show that the risk is not equally distributed. It’s clumped.”

All a virus needs is opportunity

The Reuters analysis has proven to have some predictive power by zeroing in on spillover spots. At least seven Ebola and Marburg outbreaks have been reported in Africa and 20 Nipah cases in India and Bangladesh since 2020, the last year covered by the analysis. All happened in geographic areas made up almost entirely of jump zones the analysis flagged.

The deadliest of these recent outbreaks ended in January in Uganda, where more than 160 people were infected and 70 killed by a rare strain of Ebola. Over the past two years, Marburg outbreaks have occurred in four African countries where the virus hadn’t previously been detected in humans. That includes ongoing outbreaks in Tanzania and Equatorial Guinea, where Marburg is suspected in at least 40 deaths.

Driving the rise in risk are human incursions into the world’s bat lands.

New jump zones have emerged year after year, growing in area by 16% over the past two decades. These areas have lost 21% of their tree cover over that time, double the worldwide rate. The destruction of forest, caves and other areas where bats roost and forage is forcing animals and people into closer quarters.

The human intrusions destroy bat habitat, but not necessarily the bats themselves. Unlike many other wild animals, many species of bats can adapt and thrive in habitats dominated by people.

The more bats there are, the more chances the viruses they carry have to mutate and become more infectious. And the closer bats get to people, the higher the chances that pathogens will jump species. The riskiest areas, in fact, aren’t seemingly pristine habitats where few humans are present, but those where rapid change has brought people and bats closer and more frequently together.

“If you have two cars a day on the road, the risk of accident is very low,” said Roger Frutos, who studies how viruses circulate among animals and people as research director at France’s Agricultural Research Center for International Development. “If you have 10,000 cars an hour on a road, the risk of accident is very high.”

For a virus to jump to a new species, it needs the right traits to gain entry into a host’s cells. After that, it just needs an opportunity.

In 2008, two weeks after visiting a popular cave in Uganda, a 40-year-old Dutch tourist developed fever and chills that quickly deteriorated into liver failure, hemorrhaging and fatal brain swelling. Scientists who investigated her death think a bat, carrying Marburg, may have urinated in her eye.

That spillover was limited to one patient. Other pathogens spread and endure, such as the recent Marburg and Ebola outbreaks in Africa. The worst scenarios, like the COVID-19 pandemic, can kill millions.

Each of the bat viruses analyzed by Reuters has epidemic potential, according to the World Health Organization. By identifying areas of greatest risk, the Reuters analysis shows policymakers, corporations, activists and others where spillover is likeliest at the local, regional, national and international levels.

Pinpointing the areas of highest risk is “really important,” said Jean-Claude Manuguerra, head of the environment and infectious risks unit at the Institut Pasteur, in Paris. “When you have a spark,” he added, “the fire will start.”

Mining for prosperity

Destruction of bat habitat, in addition to stoking pandemic risk, is driving some bat species to the brink of extinction and imperiling the good that bats do for the global ecosystem. The at least 1,300 species of bats play a host of roles, devouring insects, pollinating flowers and dispersing seeds.

Habitat destruction stems from some of the same economic pressures on nature that are driving climate change: people seeking livelihoods, global demand for resources, companies seeking profits.

In few places is that pressure more apparent than in West Africa’s Nimba Mountains, a 40 km long chain that erupts from the plains where Guinea and Ivory Coast meet Liberia. Capped by grass, the mountains descend into dense forests that harbor chimpanzees, antelopes, rodents and dozens of species of bat – the kinds of creatures that can transfer animal-borne viruses to humans, either directly or as an intermediary host.

Beneath the ground lie some of the world’s richest mineral deposits – the “beluga caviar” of iron ore, one mining executive called it. Scooped straight from the mountain tops, and with minimal processing, the mineral can be hauled to port and shipped to steel mills in Europe. Such natural resources exist across West Africa, where impoverished nations see them as a ticket to prosperity.

Steel giant ArcelorMittal MT.LU won the right to mine the Liberian side of the Nimba range in 2005. Since then, the company and people living in the area have cleared huge swaths of trees across the concession. In 2011, the company began mining ore destined for steel plants in Europe. Aiming to triple production by 2025, ArcelorMittal is investing $800 million to expand its Nimba mining operation.

Its presence is a boon for Liberia. With a market value of roughly 22 billion euros ($27 billion), nearly six times the size of the national economy, ArcelorMittal is Liberia’s single biggest taxpayer. In 2021, it paid $33.9 million in taxes, royalties and other fees.

But the very nature of its operations depends on two ingredients that research shows contribute to spillover: tree loss and population growth.

Satellite data shows that more than 100 sq km of tree cover has been lost across the concession – about 22% of the forest that existed in 2000. The company says farmers cut down most of those trees. That’s a typical pattern around mines in the region, because the sites attract more people than can find jobs. The newcomers often then turn to farming.

The population in the remote area around the mine grew to about 20,300 people, an 80% increase from 2010 to 2020, according to ArcelorMittal estimates reviewed by Reuters. More people are on the way.

ArcelorMittal says it employs 1,800 people at the concession and plans to add another 2,000 employees and 1,500 temporary construction workers as it expands over the next few years.

Spillover risk was already high when ArcelorMittal took over the mine, and has only increased since, the Reuters analysis shows. Company executives say they are managing that hazard.

“Here in ArcelorMittal, understanding that it’s a very sensitive environment, a very unique environment, we obviously do our best to have as little as possible impact,” said Johannes Heystek, as he gave Reuters reporters a tour of the Nimba operation in June 2021, when he was chief operating officer there.

The company points to a range of conservation and community development initiatives it is backing around the mine to minimize spillover risk. This includes programs to discourage farmers from cutting down trees and logistical support for rangers who police against poaching in the East Nimba Nature Reserve. To minimize exposure that can transmit disease, the mine’s workers are forbidden from hunting and handling wild animals.

After an Ebola epidemic started in 2013 about 200 km from the mine in Guinea, the company won a Clinton Global Citizen Award for coordinating the private sector’s response and helping the Liberian government with logistics and equipment.

Yet ArcelorMittal’s efforts to reduce risk aren’t foolproof.

In the East Nimba Nature Reserve, a protected area flanking the eastern edge of the ArcelorMittal concession, rangers say they caught several suspects who told them they had moved to Nimba to land mining jobs but ended up as poachers.

Grace Kotee Zansi, a park biologist who gave Reuters reporters a tour of the reserve in 2021, paused on a trail and pointed to broken stems: signs that poachers had passed by not long before.

“If the forest could speak, the first thing the forest could say is: ‘I’m under threat,'” she said.

ArcelorMittal’s efforts to help end – and understand – the 2013 Ebola epidemic in West Africa underscore the challenges of doing business in a spillover-prone area.

The Ebola outbreak, the largest in history, was only the second known appearance of the virus outside East or Central Africa, where it was first discovered in 1976. A relative of the Marburg pathogen, the virus is transmissible through bodily fluids. It causes hemorrhagic fever and kills as many as 90% of those who contract it.

The epidemic ravaged Guinea, Liberia and Sierra Leone, killing more than 11,000 people before it ended in 2016. Researchers estimate it cost as much as $53 billion in lost productivity, emergency response, health care and other expenses.

The epidemic began in Meliandou, a small Guinean village near the Liberian border. Palm oil plantations and logging had altered the topography heavily there before the outbreak began.

Emile, an 18-month-old boy, had played in a hollow tree inhabited by bats, villagers later told scientists. That December, Emile developed a fever. His 4-year-old sister and pregnant mother fell ill, too. All four, including the unborn child, died within two weeks, according to scientific research into the outbreak.

The virus spread rapidly in Guinea and crossed into neighboring Sierra Leone and Liberia. ArcelorMittal built health clinics and isolation centers, provided ambulances and coordinated with other companies in Liberia to help manage the public health response.

Yet while ArcelorMittal was working to end the epidemic, one of its own employees – a public health manager with understanding of the virus – disregarded company orders to isolate after falling ill with Ebola-like symptoms. Instead, he traveled to Nigeria, one of the world’s most populous countries, where he died after seeding an outbreak there, subsequent studies show.

As the illness spread – with a few cases reaching Europe and the United States – epidemiologists sought to trace its origin. Locals in Meliandou, in an effort to protect themselves, had partially burned the hollow tree where Emile played, killing and scattering the bats and inadvertently destroying possible clues to its origin. Once the epidemic subsided, researchers began catching and testing bats across the region.

ArcelorMittal allowed scientists to test bats living in abandoned tunnels on its mining concession. The testing would lead to an important discovery.

Scientists have yet to discover active Ebola in a bat. But samples of bat blood, urine, saliva and feces collected at the mine and elsewhere helped researchers identify genetic material of the same type of Ebola that had caused the epidemic. The carrier was the Nimba long-fingered bat. The researchers also found Ebola antibodies in samples from two roundleaf bats.

Both species had been living in abandoned mining tunnels on ArcelorMittal’s concession.

ArcelorMittal “assumed that the bats were carriers of viruses such as Ebola,” the company wrote in a statement explaining why it welcomed the testing. The company added that it viewed the testing as an opportunity to better understand the disease.

The findings from the Liberian bats supported evidence from prior research, in Central and East Africa, that linked the Ebola virus to the animals. It also supported the theory that a wide variety of bats might carry Ebola. The bats from elsewhere in Africa had been mostly fruit bats, so-called “megabats” that feed primarily on fruit and nectar. The species captured in Liberia were small insectivores.

Despite the challenges ArcelorMittal has faced in managing risk, Heystek remained optimistic when he was helping run the Liberia mine in 2021. He noted that authorities quickly snuffed out an Ebola outbreak in southeastern Guinea early in 2021 that killed 12 people before being contained – suggesting disease surveillance in the region was improving.

ArcelorMittal declined to comment further.

Guinea’s government, run by a military junta since a 2021 coup, didn’t respond to questions from Reuters about the Ebola outbreak or ongoing spillover risk there.

‘A growing necessity’

The governments of West Africa all have laws requiring environmental impact studies before big development projects are approved. But none requires developers and local authorities to consider the risk of spillover, let alone change their plans to account for the possibility of deadly outbreaks.

A growing number of advisers are urging governments to take outbreak risk into account. That push comes as mining giants are putting more projects – and more risk – into the pipeline.

The land covered by mining permit applications in Guinea, Sierra Leone, Liberia, Ivory Coast and Ghana would double territory authorized for exploration and extraction, to a total of about 400,000 sq km, an area larger than Germany. Almost one-third of that expansion would be in existing jump zones, where spillover risk is already high, Reuters found.

Liberia’s finance minister, Samuel Tweah, worries about the growing calls to focus more on spillover potential. “These are the kinds of things that scare investors away from the country,” he told Reuters in an interview in Monrovia, the capital.

But Gesler Murray, Tweah’s counterpart in the energy and mining ministry, said disease risk must be weighed along with broader environmental evaluations.

“We have to revisit our standard mining practices to include – very, very strongly – disease risk assessment,” he said in a telephone interview. “There’s a growing necessity.”

The assessments are especially important in light of emerging research that shows habitat destruction can backfire fast. In a peer-reviewed study of nine Ebola outbreaks between 2006 and 2014, researchers determined that seven had happened within two years after loss of nearby forest. Around Meliandou, where Emile fell ill, the timeframe was precisely the same: with a spike in tree loss within the previous two years.

Across West Africa, such rapid development has pushed humans deeper into the habitat of bats like the Egyptian rousette, known to transmit Marburg virus. The region covered by Guinea, Sierra Leone, Liberia, Ivory Coast and Ghana lost nearly a quarter of its tree cover in the first two decades of this century, according to satellite data analyzed by Reuters. That’s a total of 88,000 sq km, an area twice the size of Switzerland.

Hand in hand with that destruction has come a surge in zoonotic outbreaks.

Africa saw 338 zoonotic outbreaks over the past 10 years, 63% more than in the decade prior, according to a recent report from the World Health Organization, or WHO. Some 70% of those outbreaks over the 20-year period were viral hemorrhagic fevers including Marburg and Ebola. Viruses carried by rodents, insects, and ticks struck more frequently, too. WHO cited the continent’s fast-growing population, urbanization and encroachment on wildlife habitats as factors.


Mahama Faatey, the Ghanaian farmer, was among thousands of people across West Africa who have moved to mining areas in pursuit of prosperity. He had big plans for 2022.

In January, Faatey and his young family moved to a village in Ashanti, a southern region of the country, according to his cousin, a close friend and his village chief. He had begun growing cocoa there in hopes of finally leaving odd jobs behind. Those jobs at times included mining, the three men said.

A native of northern Ghana, Faatey moved south and spent several years bouncing around settlements including Bogoso, a mining town, and Kusa, a village three hours away, where he rented land to pursue his dream in agriculture.

Faatey’s environs had undergone profound transformation.

A quarter of the woodland along the routes he traveled had been cleared by farmers and miners in response to worldwide demand for cocoa and gold. Satellite images show scars of yellowish earth – telltale signs of “galamsey,” a local term for illegal gold mining – pockmarking the surrounding rainforest. Between 2002 and 2020, according to data analyzed by Reuters, nearly 40% of the woodland within 10 km of Bogoso disappeared.

Near Kusa, where Faatey grew cocoa, the line between cultivated land and wild habitat is a blur, patchworks of trees increasingly felled for development. Farmers there told Reuters that throngs of bats stage nightly raids of plantations, leaving a mess of guano, half-eaten fruit and partially chewed pulp on the ground each morning.

Ghanaian health officials haven’t determined how Faatey contracted Marburg. But the potential for spillover around him was as high as anywhere else on Earth, the Reuters analysis found. Ghana’s government declined to comment on that finding.

On the afternoon of Friday, June 24, Faatey told friends in Kusa that he felt ill. On Saturday, Faatey’s fever flared, said his cousin, Frederick Ankpiore. A friend bought him medicine at a local pharmacy. On Sunday, the friend took Faatey to St. Benito Menni Hospital, where doctors suspected some form of hemorrhagic fever. They took blood samples for laboratory analysis and admitted him to the ward for treatment.

By 11 a.m. Monday, according to the hospital record, Faatey was dead.

The lab results, delivered days later, confirmed the pathogen: Marburg.

Marburg has many similarities to Ebola, and a mortality rate as high as 90%. The virus has mostly jumped from Egyptian rousettes to mine workers in Central Africa since its discovery in 1967. After a 1998 outbreak in the Democratic Republic of Congo, scientists found bats living in a wildcat gold mine where many of the outbreak’s more than 100 victims had worked. Most of the miners toiled underground, tunneling by hand, with no protective equipment.

“The environment was heavily soiled with human and bat excrement,” the scientists wrote in the New England Journal of Medicine.

Once it has spilled over, Marburg, like Ebola, can spread from person to person via sweat, blood or other bodily fluids. If a male patient survives, the virus can remain in his semen for up to seven weeks. The illness can progress rapidly from symptoms including fever, headache and diarrhea, to uncontrollable bleeding, organ failure and death.

After Faatey died, his cousin and three friends went to the hospital and carried his body to the mortuary. “When I went to see him, I couldn’t recognize him,” Boamah Sonkaa, one of the friends, told Reuters. “Our brother’s death was terrifying.”

Once doctors knew of the lab result confirming Marburg, they told Faatey’s friends and family to self-quarantine. The friends and cousins had already been potentially exposed, though: They carried his body, which had been wrapped in linen and sealed in a body bag. Suzanna, his widow, had retrieved it from the mortuary the following day and, with family, transported it north to bury him.

The cousin and friends weren’t infected. But the ordeal of Suzanna, 24 years old, had just begun.

In July, Wilfred, Suzanna and Faatey’s 14-month-old baby, stopped taking milk and developed a fever and diarrhea. On July 17, according to medical records reviewed by Reuters, Suzanna took Wilfred to the hospital. He died two days later, lab results again confirming Marburg.

Suzanna, in a brief interview, said she felt stigmatized after the deaths of her husband and child. One day, she returned home to find the family’s belongings burned. It isn’t clear who torched them. During the Ebola epidemic, incineration became a common, if crude, means of decontamination by authorities and residents across West Africa.

Government health records reviewed by Reuters show that Suzanna, too, tested positive for Marburg.

But she never sickened. She self-isolated and eventually, after two negative PCR tests, left to be with family in Bogoso. Scientists say asymptomatic Marburg infections are rare, but possible.

Officials from the Ghana Health Service were anxious to contain the outbreak. In addition to tracing contacts among Faatey’s friends and family, they used social media, press releases and television to ask Ghanaians to be vigilant. They reminded residents of the dangers of bat-to-human transmission. Risk, they said in one release, “can be reduced by avoiding exposure to mines or caves inhabited by fruit bats.”

No other Marburg cases have been reported in Ghana since the virus destroyed the Faatey family.

Recently, Ghana’s government sent a team of scientists to investigate the source of Faatey’s infection. Heavy rains made Faatey’s farm inaccessible, but Sonkaa, his friend, farms nearby. Faatey himself had worked with Sonkaa there shortly before his death.

At Sonkaa’s farm, an hour’s hike from Kusa, ashanti plums, guavas and papayas lay scattered underfoot – many bearing bite marks from the previous night’s feast by bats, likely Egyptian rousettes, who live nearby. The animals often bite fruits to test them for ripeness and drop what they don’t like. Even if they do like the taste, they rarely eat whole pieces of fruit, instead chewing and swallowing juice and then spitting out the pulp, known as “fruit spat.”

“It’s the saliva, the urine and bodily fluids of the animal that spreads these diseases,” said Richard Suu-Ire, a bat researcher at the University of Ghana who led the team investigating the outbreak. “Neither you nor I could tell whether a fruit has been contaminated just by looking at it.”

A 2021 study funded by the U.S. Centers for Disease Control and Prevention found that Marburg from the saliva of the Egyptian rousette can remain infectious for up to six hours on mangos and bananas. “Six hours is sufficient time for a ripe fruit to be consumed by another susceptible animal or human,” the scientists wrote in a paper examining the issue. “In a setting such as an orchard or garden, this represents a significant public health risk.”

Knocking a papaya from a tree, Sonkaa said farmers and other locals often cut out the bite marks and eat the rest of the fruit. They also feed half-eaten fruit to pigs and other livestock. Sonkaa said he wouldn’t eat a fruit he thinks has already been nibbled by a bat.

Claw marks, however, he’s fine with. He shrugged at suggestions they could signify risk. “With claw marks it’s ok,” Sonkaa said, holding a papaya with likely bat scratches. “That one is safe to eat, I’m sure.”

Methodology Note: Guided by scientists and statisticians, Reuters created an original method for assessing where deadly viruses are most likely to spill over from bats to humans. Click here for a detailed explanation of how we did it.

—Additonal reporting by Francis Kokoroko, Grant Smith and Alphonso Toweh. Editing by Janet Roberts, Feilding Cage, Paulo Prada and Blake Morrison.