In the depths of the Amazon rainforest scientists say the world’s next pandemic could start from a cave like the Planaltina cave, which stretches more than 1.5 kilometers deep and is home to thousands of bats.

Many more caves like it exist throughout the Amazon.

Countless habitats – and bat species native to them – remain completely unstudied or undiscovered. Brazil itself hosts the third highest number of bat species in the world.

Some of the world’s most devastating viruses have emerged from bats. Scientists are studying how and why, in hopes of preventing future pandemics like COVID-19. But with limited funding, nine scientists interviewed by Reuters say they don’t expect to unravel these pathogenic mysteries anytime soon.

And researchers say humanity has been lucky to avoid a major viral spillover from the region so far.

“If you don’t do this now, there may be other outbreaks in the future and end up in the situation we are in today of not knowing where this outbreak comes from, where SARS-CoV-2 comes from. And that’s a big problem, because if we don’t know how to identify the path that this virus took, the evolutionary question and how it got to man, we can’t fight it,” Sebastien Charneau, a professor at the Biology Institute at the University of Brasilia, told Reuters.

Brazil has more land than any other country where conditions are ripe for a virus to spill over from bats to humans – so-called ‘jump zones.’

A Reuters analysis found that Brazilian jump zones have grown more than 40 percent over the past two decades. That’s 2.5 times faster than similarly risky areas worldwide.

Driving the risk is rapid deforestation of the Amazon region. Scientists say deforestation causes stress in bats and some studies have found that stressed bats could carry more viruses and shed more germs in their saliva, urine and feces.

“It is very sad to know that we have great potential to discover and prevent new epidemics, new pandemics and this is not being taken into account, nobody is thinking about it. On the contrary, we are currently having a very large investment in dismantling the environment,” said Ludmilla Aguiar, a biologist at the University of Brasilia.

Destruction of bat habitat soared during the administration of Jair Bolsonaro - a far-right populist. His government rolled back environmental regulations and slashed funding for scientific research. On his watch, Brazil’s health system buckled under COVID-19.

Bolsonaro left the presidency in January 2023. His lawyer said the former president declined to comment.

Scientists and health experts warn the country is still ill-equipped to spot a dangerous pathogen – despite chances of a novel virus emerging from the region being high.

Bolsonaro’s successor - President Luiz Inacio Lula da Silva - has promised to eliminate deforestation in Brazil by 2030.
But that would require him to revamp Brazilian law – and powerful legislators allied with Brazil’s farm lobby won't make his efforts easy.

A farm caucus representative told Reuters that the group supports his efforts to halt illegal deforestation, but that legal tree clearing is needed to guarantee food and energy security.

Lula’s health ministry said it monitors the risk of zoonotic spillover daily through several networks and programs and it's studying ways to improve surveillance.

Meanwhile, deforestation is continuing at a steady pace. Each new incursion offers another opportunity increases for a new and deadly pathogen to spill over - and spread to the rest of Brazil - and to the world.