CDC Director Tom Frieden, who is unofficially leading the U.S. response to Ebola says the virus becoming airborne is a possible but unlikely outcome in the current epidemic:
The rate of change [with Ebola] is slower than most viruses, and most viruses don’t change how they spread. That is not to say it’s impossible that it could change [to become airborne]. That would be the worst-case scenario. We would know that by looking at … what is happening in Africa. That is why we have scientists from the CDC on the ground tracking that.
The disease kills roughly half the people it infects, and lacking a vaccine or cure, its traceable chain of transmission through bodily fluids is one reason officials believe they can contain it.