Hi,
I can certainly understand your concern over the flu. We were just at WDW (12/6-13) and the flu was weighing heavily on my mind. There were a lot of news reports about it the night before we left, which made me especially paranoid. Since my doctor is out of the injectable vaccine, and doesn't have the flu mist I'm still feeling paranoid.
Anyway, my approach was to buy the anti-bacterial handgel that dries on your hands and "sanitize" everyone about 10 times a day, especially right before eating, and after the kids where at any playgrounds. Also did it after they washed their hands in any public bathroom, since the last thing they touch is a door that lots of people who DON'T wash their hands also touch. I don't know how much good antibacterial cleanser is against viruses, but I figure the alcohol in it probably kills alot of everything.
Good luck, and I hope you have a happy and healthy trip!