Cyrodiil is a dangerous place in The Elder Scrolls IV: Oblivion, and disease can be just as much of a threat as bandits or Daedra. Most diseases are just minor afflictions that sap your stats or cause small debuffs, but the Porphyric Hemophilia is a condition that can ruin your day, literally, because it turns you into a vampire.
If you don't rid yourself of Porphyric Hemophilia quickly enough, you'll be stuck looking for the cure for vampirism. Being a vampire in Oblivion sounds cool on paper (and it does come with some unique benefits), but vampirism is a prison you won't want to wind up in by accident.
