Well said Mindy! I have an isolation cage just for new purchases too. I also give the full gambit of meds to make sure any new arrival is clean and healthy before letting it assimilate into the flock. My biggest regret is that I did not start this procedure sooner, perhaps I would not have...
It is very important that you isolate any new birds that you bring into your aviary for at least two weeks for observation. Better yet, deworm and treat them for Coccidiosis before letting them run with your birds.