Bird Flu can be spread by, well, by birds.
And it seems to have left SE Asia, & is spreading by birds, especially waterfowl.
http://www.recombinomics.com/News/06070502/H5N1_Sheep_Mongolia.html
If this is true, we can expect a wider Human outbreak, soon.
We can quarrantine people fairly well, but not migratory birds.
IANAMicrobiologist, but I think that if it’s actually bird flu, it actually sucks on two levels, in that a)it’s spread so far, and b)it’s jumped to a mammalian species (and one that hangs out with people, too.) Once it’s mutated enough to easily infect a mammal, it’s much closer to being able to easily jump to/among people.