It's amazing that something as small as a virus (typically 80 to 100 nanometers) can sneak into, replicate and attack a host. Further, it can be so incredibly effective so fast that the victim has little warning of what is coming. The cool thing is that when your body figures out how to fight the intruder it usually wins. Scary stuff none the less, if something really nasty ever came up (I could name a dozen SCIFI movies) we'd be toast.
Had to look this up... a nanometer is 1x10(-9)... that's one billionth of a meter.
