>>I'm going back to the original statement - "no symptoms/fever - zero risk of transmission". That's mixing approximations with an absolute.

Absolute Risk = (# incidents)/(# exposed). For Ebola, the demonstrated (# incidents) of transmission is 0 without symptoms. You can do the math.

So far the hypothesis has survived months of challenge and you can be sure that people are looking hard for the single example that disproves the current position. They *want* to find it if it exists, not just because they will be even more famous than Kaci but because there's no shame in changing your mind when the facts change, especially when it comes to the safety of folk at home.

You probably know, but: Ebola is contracted through mucous membranes or via breaks in the skin. For caregivers who are not having sex with patients or other close contact without a space suit, transmission is possible by getting virus in eyes or mouth or into cuts or needlestick injuries. These things do all happen despite best efforts, but so far no recorded transmission except from somebody symptomatic or from infected meat outside the medical facility. Inside the medical facility, for virus to penetrate the space suit is going to involve a recorded breach, so there is hard data here.

If you were correct that transmission is possible without symptoms, these caregivers would need to wear space suits at all times even when socializing amongst themselves and ought to be quarantined for 21 days in their suit before heading home on a plane shared with hundreds of innocents and arriving at an airport where thousands could be exposed. IOW the proposed Stateside quarantine isn't even rational as it could result in thousands of innocent fellow travelers carrying infection widely before the infected caregiver shows her first symptom.