According to this chart, the right time to start worrying and to begin organizing public rallies is when you start bleeding inside and outside and become a walking bioweapon.
Naturally, a rational person concerns himself with such matters a bit earlier. But the author of the chart obviously have never seen a rational person in his whole life.
I think the point is more the vector of spread: how many people are exposed to such bodily fluids? (Most people go out of their way to avoid them.)
Those that have contact [parents and baby-sitters] can be fairly sure of their kid's condition regarding Ebola-infection (unless they're irresponsible and sending them to daycare and/or public school — who knows what filth is there). And the remaining are people that have such exposure (nurses, doctors, etc) should already be aware of this.
IOW, the news-hype is just that: hype.
Take a good, calm breath and consider the actual facts and plan on that; nobody needs you running around in hysterics, not even you.