The people in those countries will just go to a different country and fly out. Border security isn't that great in Africa.
Medical tests would require holding everyone for 21 days to ensure they weren't infected. The logistic on that are insane.
The solution is to contain and cure IN Africa and put out the hot spots as the appear elsewhere.
But fewer will be able to get out.
I'm no epidemiologist, and media information on Ebola is so bad that I feel like I have no real knowledge of it at all. However, it seems to me that when dealing with an infectious and deadly disease, travel restrictions seem like a very, very, good idea. Sure they aren't perfect, but they are better than nothing. Of course, that's just a "common sense" view, i.e. uninformed opinion based on other knowledge, which may or may not have any legitimate application to this one. Nevertheless, I am confident if you stop all flights out, there are some carriers of the disease who would have left, but end up not leaving. Would that actually slow the spread of the disease? That's where you need an epidemiologist.
On the second part of your statement, though, I have to agree 100%. If we want to prevent infection in the United States, the best way to do it is to cure, treat, and prevent as many cases as we possibly can in Africa.
I think it's time the United States and other developed nations took some drastic, severe, even unprecedented actions to contain Ebola in Africa. I think we should make this a top priority, and do whatever it takes, regardless of the howls of protest. Yes, yes, those guardians of freedom will howl like stuck pigs at what I would propose, but according to the World Health Organization, we can expect 5,000 cases a week in Africa by the end of the year. With that rate in Africa, is there any doubt that there will be cases in America, Europe, and elsewhere. This is not time to play nice. We should do whatever it takes to fight this disease, EVEN IF IT MEANS RAISING TAXES!