Liberians will make it here while incubating. There is no reason to expect smarter or dumber viruses to be in those incubators. There is a bit of selection in cases of Liberians with a few bucks to travel versus bush meat eating, corpse washing cultists, but not a lot. What I expect is more of the same old deadly, but spreads with difficulty kind of Ebola showing up here.
http://www.newsweek.com/2014/08/29/smuggled-bushmeat-ebolas-back-door-america-265668.html?piano_t=1
Also a 2009 article many more on Google
http://abcnews.go.com/Nightline/IntoTheWild/bushmeat-africa-sold-open-market-us/story?id=9312518