Why would you want to turn your follower into a vampire? You'd lose your source of infinite blood!
There is no short supply of that...by far.
I would love to see this implemented into the Vanilla game. There is at least one mod that allows you to turn other NPCs and they will then feed themselves. Great stuff, indeed.
How do you use spoiler tags? I want to reference an in game town where they had vamps trying to take over by doing something similar to what the OP is saying.
Yeah, I'd like to turn Jenassa into a vampire. Obviously, there should be an option whether or not to inject your disease into the victim or else everyone in Skyrim would be a vampire.