Uh-huh.
We can add to our list of people those who come from ebola country no matter how many countries that eventually includes. For now it is four countries. Whether it spreads or not is not our problem. It is the problem of those countries who do not stop it at their borders.
If it was going to be all of Africa why wouldn't it already be all of Africa?
EVD was first identified in an area of Sudan that is now part of South Sudan, as well as in Zaire (now the Democratic Republic of the Congo). The disease typically occurs in outbreaks in tropical regions of sub-Saharan Africa.[1] From 1976 (when it was first identified) through 2013, the World Health Organization reported a total of 1,716 cases.[1][4] The largest outbreak to date is the ongoing 2014 West African Ebola outbreak, which is currently affecting Guinea, Sierra Leone, Liberia, and Nigeria.[5][6] As of 10 October 2014, 8,376 suspected cases resulting in the deaths of 4,024 have been reported.
If it has not sread to the entire world since 1976 why do you believe it will spread to the entire world this time?
After we have stopped ebola-exposed people from coming here get back to me in a year or so and let's discuss it again. Meanwhile try not to hyperventilate while you imagine that we should not protect Americans with a simple "No" to the ebola-exposed.