Dr. Richard Webby, Virologist at St. Jude Children’s Research Hospital in Memphis, Tennessee, studies how influenza viruses evolve and move between animals and humans.

We tend to think of the flu as something seasonal, a nuisance we can fend off with a shot and a bit of luck. But what if the real threat isn’t just circulating among humans, but quietly evolving in birds?

Dr. Webby has spent his career studying the invisible boundary where animal viruses spill over into people. Much of his work focuses on influenza viruses that circulate in aquatic birds, strains that most of us rarely think about but that can sometimes jump species.

In this episode, Dr. Webby walks us through the complex and often surprising world of influenza A, including the H5N1 virus currently making headlines, and explains how scientists are working to understand which strains could pose the next major global threat.