When Dr. Richard Besser was reporting from the Ebola crisis in Liberia in 2014, he knew how to keep himself safe. But, says the health and medical editor for ABC News, there was more at stake than his personal welfare.
Carnivores eat their prey from the outside, author David Quammen writes in his 2012 book Spillover. Pathogens attack from within and are no less deadly. They enter our bodies unseen when we breathe, have sex, take a drink of water or just walk in the woods.