Bird flu is very dangerous but at the moment you can only contract it from direct contact with the birds - particularly I think with their droppings - so it's only really a threat to people working in the poultry industry.
The fear is that one day the current strain might mutate to be transmissable from human to human which would be a major health panic.
It's believed that the great flu epidemic after WWI was an Avian flu mutation of that type.
How probable is such a mutation? - nobody knows