Yes, very scarey stuff, and the latest one I did read on redtailboa forum. I have a python and a boa, our python came first and then the boa (from a recommended high-end morph breeder). I have always kept them in separate rooms. They never come out at the same time, and on days they do both come out the python is handled first then the boa and I've always been careful about them not using the same bowls. It's supposed be transmittable, as you say, by mites, snakes touching, bodily fluids etc, but in this case they're thinking it is indeed airborne virus too.
In boas I've heard it can be controlled, but in pythons it is always fatal. It gives me the creeps to go into pet stores and see python babies kept in with boa babies in the same incubator units.
Does the boa have to be showing signs of the condition in order to infect a python? Or can it give it to a python anyway even if it's a dormant and as yet undiagnosed condition? I don't think mine have a problem and I don't handle any other snakes from anywhere else unless I shower afterwards, but am getting a bit paranoid about it. I would have thought if the boa had it my python would have been infected (and died) by now.