The NSA has already shown this to be relatively trivial. Don't think for a second the government wouldn't harness that knowledge in an emergency situation such as an Ebola outbreak within the US.
The NSA is excellent at tracking communication contacts that establish the existence of relationships (notwithstanding the potential of false positives). And this would also work for tracking someone driving around in a car running errands in specific places.
But if someone arrives in a US city unwittingly carrying Ebola and gets on a crowded bus or subway car, that's not so easy to track. Likewise if the person goes to a nightclub or other crowded place. Suppose it's a returning American who attends a baseball or football game - the NSA may well be able to ID almost everyone who attended the event, but trying to screen/isolate tens of thousands of people who might have come in contact with an infected individual wandering around a stadium is easier said than done.
They can track your location via a cell phone that nearly everyone carry's with them at all times.
If an infection does come over, then expect people the laud the NSA's spying because it'll be the thing that makes it possible to identify, target, and quarantine.
That could change in short order - don't you remember the Liberian guy who turned up in Lagos? If he had traveled a few days earlier he would still have been infectious but might not have been identified as such on arrival.
