If there is one sick bird in a coop full, does that mean they have ALL been exposed? Is it true that only some of them actually 'get sick' from it? Is it true that it doesn't hit all at once? Mine seem to be getting sick one by one, weeks apart... All ages... Over 2 years to much younger. I did find that Muscovey ducks CAN NOT get it...... BUT............... If the ducks live in the same coop and after all chickens are gone, with everything clean, disinfected (with the best stuff) and some time, Maybe a couple or 3 monthes. WILL THE DUCKS TRANsFER IT TO NEW CHICKENS??????