Bats harbor hundreds of coronaviruses, and spillovers aren’t rare

Three years ago, NPR accompanied disease ecologist Kevin Olival on a field trip to Malaysian Borneo.

Olival, who is with the nonprofit research group EcoHealth Alliance, was there to trap bats and collect samples of their body fluids. He and his collaborators would then test the samples for viruses. Bats are known for carrying some dangerous ones, particularly viruses that have the potential to kick off global outbreaks through what's called "spillovers" — instances of an animal virus jumping into a human.

So the researchers were on a hunt for the next big threat.

The results of their work put the current coronavirus outbreak in China in a wholly new light. Scientists say it was caused by a spillover event. And the findings from the sample collection project suggest these kinds of spillovers have actually been quietly taking place in China for years.