Why? Simple: Doorknobs.
Flu germs can live on a doorknob for up to 48 hours. You sneeze on your hands, open a door and that doorknob is now typhoid Mary. So, that is bad. Easy to catch the flu. What about Bird Flu?
Have you ever seen a bird open a door? No hands, right? Not going to happen. They don't even have the ability to sneeze on their hands or wipe their nose.
Bird Flu is not going to spread from birds sneezing on their hands and opening doors. Case closed.
Now if the Chinese start tainting bird food like they tainted baby milk, we need to worry. The moment birds start mutating and growing hands... Well, we are deep in the brown stuff that comes out of the back of bulls.