You can't take a knife on a plane anymore, but you can get on carrying a virus.

The more cases of Ebola infection we have, the more chances there are for the virus to mutate in a particular way that adapts it well to living in humans, replicating in humans, and perhaps transmitting from human to human.

Viruses have to live somewhere. They can only replicate in living creatures. So, when the Ebola virus disappears between outbreaks, it has to be living in some reservoir host, presumably some species of animal.

One of the things that's particularly nefarious about Ebola is that it continues to live in a dead person for some period of time after death. A person who's been dead for a day or two may still be seething with Ebola virus.

Ebola isn't a respiratory virus. It doesn't spread through the airborne route. So it's not likely to spread like wildfire around the world and kill tens of thousands or hundreds of thousands of people. That's what I think of as the next big one.

He did walk behind me, ... But it wasn't a shovel he was carrying. It was a knife.