A study completed just recently shows that raw milk is infectious, at least in mice. HTST (high temperature, short time–this is the most common method used in the US but not most of the world) pasteurization mostly neutralized the virus but not entirely. Batch pasteurization neutralized it. Just FYI.
It’s the flu, a respiratory disease.
There may be other vectors (like raw milk), but airborne is going to be the main route for birds.
Might be the case that some places have multiple buildings and can keep some chickens away from others. I don’t know whether that’s enough isolation.
A study completed just recently shows that raw milk is infectious, at least in mice. HTST (high temperature, short time–this is the most common method used in the US but not most of the world) pasteurization mostly neutralized the virus but not entirely. Batch pasteurization neutralized it. Just FYI.