For millennia, bat viruses lurked in forests across West Africa, India, South America and other parts of the world. But, undisturbed, they posed little threat to humanity.

No longer, a new Reuters data analysis found. Today, as more and more people encroach on bat habitat, bat-borne pathogens pose an epidemiological minefield in 113 countries, where risk is high that a virus will jump species and infect humans.

Bats are linked to many of the deadliest disease outbreaks that occurred during the past half century - including the Covid-19 pandemic, which has killed at least seven million people and has its roots in a family of bat-borne coronaviruses. Though scientists are still trying to figure out how that virus came to infect humans, dozens of other outbreaks can be traced to human incursions into areas thick with bats.

To examine where the next pandemic may emerge, Reuters used two decades of disease-outbreak and environmental data to pinpoint the places on the planet most vulnerable to "zoonotic spillover" - the term for when a virus jumps between species. Viruses leap 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, faeces, blood, or saliva.

Reuters reporters spoke to dozens of scientists, read extensive academic research and travelled to bat-rich countries across the globe to learn how human destruction of wild areas is amplifying pandemic risk. Our data analysis - the first ever of its kind - revealed a global economic system colliding with nature and putting people's health at risk, as bat-rich forests are cleared to make way for farms, mines, roads and other development.

Here are key takeaways from our examination:

• Reuters found more than nine million square kilometres 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," span the globe, covering six per cent of Earth's land mass. They are mostly tropical locales rich in bats and undergoing rapid urbanisation.

• Nearly 1.8 billion people - more than one of every five of us - lived in areas at high risk for spillover as of 2020. That's 57 per cent more people living in jump zones than two decades earlier, increasing the odds that a deadly bat virus could spill over. Moreover, those people are living closer together, intensifying the chances that a disease outbreak will develop into a fast-spreading global pandemic.

• The Reuters analysis found high spillover risk in locales including China, where Covid-19 surfaced; neighbouring Laos, where scientists have identified the closest relatives in wildlife to the virus responsible for the current pandemic; India, where half a billion people live in fast-expanding jump zones, the most of any nation; and Brazil, which has the most land at risk of any country, as humans ravage the Amazon.

• The catalyst for outbreaks isn't bat behaviour, scientists say, but our own. Thirst for resources - iron ore, gold, cocoa and rubber, to name a few - is driving unchecked development of wild areas and boosting the risk of global pandemics through greater contact with animals, scientists say. The world's jump zones have lost 21 per cent per cent of their tree cover in almost two decades' time, double the worldwide rate.

• Pressure on once-remote woodlands gives viruses a chance to spread and mutate as they leap among animal species, and eventually, into humans. The deadly Nipah virus in recent decades spilled over from Asian fruit bats into pigs, and from pigs into people. Nipah more recently has proven able to infect humans directly through contact with the bodily fluids of bats.

• Humanity is destroying crucial habitats before scientists have time to study them. Not only does development bring people into closer contact with pathogens that could have pandemic potential; it also eliminates secrets nature may hold that could be of value to science. For instance, bats' ability to live with multiple viruses, without succumbing to many that may be deadly for other mammals, could yield important knowledge for the creation of vaccines, medicines or other innovations.

• Governments and corporations are doing little to assess risk. In bat-rich Guinea, Sierra Leone, Liberia, Ivory Coast and Ghana - where Reuters found pandemic risk to be among the highest in the world - pending applications would double the territory used for mining exploration and extraction, to a total of 400,000 square kilometres, an area larger than Germany. Almost one-third of that expansion would be in existing jump zones, where spillover risk is already high. Though those countries require mining companies to assess potential environmental harms that new concessions might cause, none require companies to evaluate spillover risk.

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Source: Reuters