Doesn't have to be.
They could make the 15 min test available, and then mandatory for any flying out of the affected countries, and that right there, would nip it in the bud internationally.
Instead, the current measures are going to do NOTHING to avoid international spread of it, as non-symptomatic carriers are going to pass the temp screens with flying colors (as the guy in Dallas would have, who then died), get home, then think they have the flu, and spread it to others before realizing they have Ebola. (and of course, those others spread it, and so on).
Mind boggling. It's almost as if they WANT this thing to spread. Even my inner conspiracy nut can't fathom that one, but it is what their actions suggest. It's either that or gross incompetence and stupidity, and both are pretty scary prospects.