I'm with Judy. Look at the timeline of the doctor who tested positive in NYC.
Timeline for New York Doctor Who Has Ebola - ABC News
I don't understand the nurse who is complaining about quarantine (or anyone else) pinning everything on one temperature check at the airport upon returning to the US. One temperature check is not enough for clearance.
As for why medical personnel here are not being quarantined after treating cases here in the US -- probably should. However, Duncan's case aside, conditions in hospitals here are far better than in the countries afflicted in Africa. Personnel here are dealing with one case and not surrounded by hundreds.