Well, NAIS really has nothing to do with disease (think, practically, how on earth a number will fight disease? It will only tell them where the local flocks are when some factory farm gets some disease that spreads like wildfire because of the monoculture and they know whose backyard flocks get to die, sick or not). It's mainly about foreign markets and big agri-biz. It will cost you--when is stuff like this ever free?
This is a possible scenario for you to consider. It may not go exactly this way, but from what I've read, it's possible. I have a Tyson guy a few miles down the road from me. Say, a wild bird flies in through the big sliding door on their metal building. It has some form of avian disease and is trapped in the bldg up high, probably unnoticed at least for awhile. The doors are opened, the bird either flies out or is already dead among the birds he's raising. When the disease is caught and reported, depending on what it is, the kill zone is established and all the flocks within a certain range are killed without testing (they do not have to test to determine if these flocks are infected--after all, to them, time is of the essence and that takes too much time).
Were my chickens several miles away up on the mtn ever exposed? Highly unlikely. Do they care that I am raising highly endangered heritage breeds that are not easily replaced or even irreplacable? NO. A chicken is a chicken is a chicken in this case. And it's irrelevant that they are not ill or even exposed--they were in the kill zone, period.
So, how is my premises number assigned to me by the USDA going to help anything? It won't. It will however protect the financial interests of big agri-biz. And help wipe out my own ability to feed my family. Next thing you know, we'll have to be asking, "Please sir, may I put a tomato plant on my deck??"