There have been other outbreaks - separated by a few years. I have read theories on Ebola in it's current form being a bioweapon, and that these outbreaks are weapons tests.
One factor that supports this kind of thinking is that a pathogen that rapidly kills its host usually does not survive as a viable organizm - so why does it keep cropping up?
Another thought along these lines is that we know the PTB want to reduce the world population, and wouldn't a release of this stuff at the end of the Olympics just before everyone flies home be a dandy way to do it? Sorry - just my devious paranoia...