I have to confess that part of me wonders whether this has been blown out of proportion, that said it is far better to be safe than sorry.
Basically it involves people using their common sense. Think twice about travelling to Mexico or Texas, sneeze into a hankerchief or paper hanky, then bin the hanky. Clean surfaces after use etc.. It shouldn't have to be told, but as we all know, it's amazing how many people don't use their common sense!