Bioterrorism is like earthquakes, you should think in order of magnitudes. If you can kill 10 people that's a one, 100 people that's a two... Bioterrorism is the thing that can give you not just sixes, but sevens, eights and... ...
With nuclear weapons, you'd think you would probably stop after killing 100million. Smallpox won't stop. Because the population is naïve, and there are no real preparations. That, if it got out and spread, would be a larger number.
