320K Unknown Viruses Lurk in Mammals

An ambitious new study by some of the world's top virus experts estimates that at least 320,000 still-unidentified viruses are lurking out there among mammals—some presumably with the potential to jump from animals to humans, reports Smithsonian. That's the scary-sounding part. The better part is that the number is much lower than expected, and researchers in the journal mBio write that scientists could probably identify 85% of them with an investment of $1.4 billion. The remaining 15% would cost an additional $5 billion or so, and the researchers argue that the money would be a wise investment, reports PhysOrg.

"By contrast, the economic impact of the SARS pandemic is calculated to be $16 billion," writes one of the researchers. "If we know what's out there, we'll be a lot better prepared when a virus jumps over into a human population." So how did they get the 320,000 figure? The researchers zeroed in on one species—a bat in Bangladesh known as the flying fox, reports the BBC. They took 1,900 samples from trapped bats (all of whom were later released) and discovered that they harbored about 60 viruses, only five of which were previously known to science. From there, they extrapolated to all mammals. Further studies are underway to fine-tune the estimate. (More discoveries stories.)