[FITZ]

I think this is why we're always reading of some horrible new epidemic that is bound to kill us all ---swine flu, hanta virus, mad cow disease, Legionnaires disease. Every year it seems there is some new disease that we should fear and they never are as bad as they first seem. Ebola can't get far in human populations because it jumps species and immediately kills it's hosts ---a cold or bacteria that can co-exist with a host that can be a carrier has the best chances to spread. Even with weak cross-immunity, you have some protection until your immune system is able to fight off the virus with specific antibodies --that takes about 3 weeks.

[Movemout]

"Ebola can't get far in human populations because it jumps species and immediately kills it's hosts "

The latter part of your statement is relevant. Ebola is too hot. It burns through the hosts available so quickly that new hosts are not available after a quarantine is initiated. If there is ever an airborne variant of Ebola then all bets are off.