[tjradcliffe]

While it is tautologically true that if Ebola were to become capable of airborne transmission it would be much more dangerous, there is considerable evidence against the proposition that it is "just one mutation away" from such capability.

Ebola has been around for a long time, and by your own reckoning has had billions of opportunities to mutate into an airborne form. It has not done so. Why not?

The Ebola genome consists of about nineteen thousand base pairs, compared to three billion in the human genome. While that represents a vast amount of combinatoric complexity, biochemical capabilities are not magic. They are not conjured into existence by the wave of a mutational wand, but have to have some substrate in existing functionality, which is why species exist: they are are islands of relative genetic viability in a sea of chaos. An incremental move away from the stable centre will in general be detrimental to the organism, and it will, in the overwhelmingly most common case, require many small, fortunate steps to add a genuinely new capability.

The fact that Ebola has not yet become airborne despite its many opportunities to mutate and do so suggests that we are dealing with a typical case here: that the current genetic configuration of the virus is more than "one mutation away" from being airborne, and it may well be a case of "you can't get there from here" (at least not easily enough for anyone to very worried about in a country where cars kill tens of thousands of people a year and people with guns kill thousands).

Nor does it follow that an airborne form of Ebola would be as deadly as the current form. With such limited genetic material to play with, an airborne virus would necessarily have to change some other characteristics, any of which could reduce its ability to kill.

[crimsonalucard]

There was an airborne strain of ebola that made it to American soil. The catch was that this strain only infected monkeys.

http://en.wikipedia.org/wiki/Reston_virus