Swine-Chicken-Flu?
This thing is a "catch-all" word used by the Feds to kill off chickens.
It mostly happens because you raise chickens too tightly together with too many chickens.
And then they PCR test them, and announce, these chickens should all die.
You look for sick chickens in your flock and then isolate them. Being slow/sluggish. Or being picked on by the other birds. Put them in their own cage for a while till better, try to reintroduce to the flock.