That's why they had the horrible episode in Hong Kong a few years ago, they thought maybe something like the 1918 flu was coming back because young people were dying of the flu and it turned out to be transmitted from chickens, so they killed all the chickens, ducks and geese in Hong Kong. In general we can't get it directly from birds. They get the flu all the time and don't get sick. They have an enzyme that we don't have. So in order to get a bird flu something has to change in it.
Pigs can get flu from birds and pigs can get flu from people.
They can be sort of a mixing bowl. It's a linguistic thing. They started calling it a flu before they actually learned there was such a thing as a virus. It's different viruses causing different things. That's why it's so scary.