Personally, I would think that if any of your snakes have IBD, it will spread in your collection. You can sanitize your hands, but what about feeding tongs, or other herp supplies? It would be very difficult not to spread even with religious sanitizing, IMO. If you are going to keep boas and pythons, only buy from breeders that keep both. If the breeder you are buying from has boas with IBD, their pythons would likely be dead. I also suggest only buying from reputable breeders.