That's a very good reason for wizards to have done this to start with :)
And the talent-to-talent contamination definitely makes sense. As for the contaminated healing, that would work too, so long as we can figure out a way to actually get rid of the plague at some point! Oooh maybe once it's figured out, someone with corrupted necromancy could do something about it.
Though let me not rush to make decisions before things play out. Stuff can come up that would make things work in a way we didn't expect :) Let's get this plague rolling! If it's easier for everyone, mods can get the ball rolling with a 'herald' post (which reminds me that Willem needs a herald!)