What I did: put on full suit of daedric <or some other high AC armor> stand in middle of a pile of vampires wait about 20 minutes check on character.. you have contracted arglebargle whatchamacallit may wanna wait till you level up a bit and have good armor, but it IS a common disease <as said above> and so if your like an argonian, you almost can't get vampire disease <wah> but if you do, it looks cool B)