Yes, a pandemic can occur even if the pathogen is not transmitted through there air - see HIV/AIDS.
Airborne and droplet spread make for fast spreading and hard to control epidemics. If something spreads through bodily fluids only, it's easier to do contact tracing and put the right measures in place. I think that's what people want to highlight if they say that Ebola is not airborne.
Actually, there was a study earlier this year[0] which showed, with better data and more rigorous treatement of the fluid dynamics, dropplets can travel much farther than previously thought. [1] has a summary of the research, in case the article is not available. But their basic conclusion is that, depending on the size, droplets can travel up to 200 times farther than previously thought, because they are carried along with the "cloud" associated with the sneeze.
[0] http://journals.cambridge.org/action/displayAbstract?fromPag...
[1] http://www.huffingtonpost.com/2014/04/09/sneeze-cloud_n_5110...
http://www.ncbi.nlm.nih.gov/pubmed/205151
In that study, 11 of 15 hand-contact exposures to a rhinovirus led to infection, which is not 80%, but it's within the margin of error. Notably, it was almost as good as large-particle aerosol exposure at spreading the virus.
But yes, the important point is that you don't need an airborne virus for a pandemic. Every virus is different, but there's this public fixation on "airborne" transmission that is a bit of a red herring. Ebola is doing just fine without it.
Considering that there are still regular flights from African countries to the US, that would be a large number of people.
Maybe that screen should be applied only if you have developed a symptom like a high fever...?
So at the moment, this "screen" is an easy way to rule out Ebola in a patient with potentially Ebola-like symptoms. Obviously we wouldn't expect everyone who has recently been to Africa has Ebola. I didn't downvote you, but I expect this is the reason why you're getting downvotes, not a misunderstanding about your question.
Is there a risk here? Yes, a small one.
I understand, but am frustrated by, the number of people who keep repeating "it's not airborne", as if this is some kind of definitive argument that a virus cannot spread here.
Something like 80% of cold/flu infections happen via "bodily fluids" -- people snot on a surface, someone else touches the surface, then touch their face, etc. This is an effective means of virus transmission. A virus doesn't need to be airborne for a pandemic to occur.
That said, we have a number of advantages over rural Africa in dealing with illnesses -- we have high standards of sanitation, good electricity, clean water, and our population is generally not afraid of physicians (with notable exceptions in some minority communities). But our biggest advantage, by far, is that Ebola isn't endemic here. Our best and most effective screen is "have you been to Africa recently?"
If that screen loses its effectiveness, you start to have to worry about every patient presenting with a fever and diarrhea, and the epidemiology becomes quite difficult. We're not really prepared for everyone with a fever and vomiting showing up at the emergency room...and it won't take many patients (a few thousand, say) for things to get tense.