Couple ways to look at it...
The amount of contagion accelerates substantially the longer someone is sick. Accordingly the amount of contagion per exposure is dictated by the type of exposure. So someone touching heavy droplets, sweat spit, etc will have less germs per volume than say blood or feces.
Incidentally how one is exposed and how much contagion is in that initial exposure dictates how one can be treated and all indications are that only heavy droplet exposed people have beaten the disease save for those who’s personal immunities rise to the rescue.
Problem here is this...
each exposure in the states raises the risk of a few things.
1. Mutation
2. Exposures to more contagious fluids
3. Outpacing insurance willingness.
4. Outpacing medical willingness.
You forgot a few :
5. Outpacing medical ability (as in MSF overwhelmed in Liberia, Guinea, and Sierra Leone)and turned 30% of patients away.
6. Outpacing availability of medical supplies (need for saline IV which is already in short supply) ,
analygesics , and anti-diarrhea medications, PAPPR (space suit with air supply), gloves, booties, etc.
7. Overcomming insurance liability for Health Care Workers who are willing to remain and work intimately with patients.
8. Getting replacements for HCW (nurses/doctors/aides) who abandon Ebola care, and just walk away.