mitzi, kass, and anyone else that just got all scared, any bird from any flock OTHER THAN YOUR OWN, has differant diseases than your birds do. the disease itself is the best medicine against itself. low level exposure is the best defense against the any disease.So then anyone who has ever had a mixed flock w/ a spitz or spitz mix also has this? Or anyone who has gotten any chicken of any breed that also had a spitz or spitz mix in the flock w/ any other chicken also carries it? Or almost any bird purchased at an auction that had a spitz or spitz mix or had been kept on a place w/ a spitz or exposed bird can have it or carry it? What I'm saying is it is out there and not just confined to spitz's anymore.
If it is going to keep you up at night worrying over it then don't get them, there are other birds w/ top knots, but don't kid yourself that if you don't get a spitz your (the general you not specifically you) flock hasn't been exposed if you have brought any bird into your place that has ever lived elsewhere or been to a show or auction.
So not meaning that every bird that has been to an auction, show or lived elsewhere has it or carries it, just that any of them COULD have/carry it.
as for "walking" a disease from one farm to another, most diseases die very quickly after leaving the host.
best thing you can do is quarantine your birds for a while.