The CDC is still worried about it spreading to humans. They gave the workers that euthanized the flock tamaflu.That was a completely different strain of avian flu in China. That was H1N1, and this is H5N2 and (so far) is not lethal to humans. The CDC has yet to explain the appearance of this variant of the virus. The H5N1 strain made it across the border from Mexico last year and has killed several people in AZ alone, but doesn't seem to affect poultry.
I am sure I read that this strain came over from Europe though. It is likely a mutation of the original one.
The vector of infection is the same though--comes from Geese migrating and using the fly ways.
Someone did target a commercial poultry place recently--they messed up the ventilation system and killed a big poultry house full of birds. That topic gets us into stuff we cannot post about on BYC though. It is in the rules of use for the site.