Crzychicken, since her birds were vaccinated by McMurry, you can call them and ask whether the vaccine they use creates a carrier state and how long they need to be quarantined from non-vaccinated birds.
But I mostly agree with Horsejody's comment about quarantining new birds, and that the lack of it is probably the original cause of flock deaths.
But I mostly agree with Horsejody's comment about quarantining new birds, and that the lack of it is probably the original cause of flock deaths.