Sneezing and coughing on crowded buses/trains/events. Yes, they could do that first.
I don't really believe in this. Ebola supposedly killed 4000 people in nearly one year. (Please note that lots of cases were only suspected to be ebola, but no rock solid proof for that.) In addition those places are the poorest countries on the world, right after some civil wars, no sanitation, contaminated tap water, poor hygienic standards, poor health care system, incompetent authorities. I think those bio-terrorists would be more successful even by spreading flu. That kills 250000-500000 ppl worldwide each year.
I'm sure they will turn up with something pretty soon if there will be enough demand. If can't then they can pull Tamiflu and Relenza out of the hat again as wide spectrum antiviral drugs .
Its not about # of deaths, its about amount of terror (government over-reaction in response to politically motivated violence).
Wars were started over a little over 3000 deaths on 9/11.
Flu virus just doesn't have the effect.