Board Thread:Lore Discussion/@comment-13436964-20130726062712/@comment-16047389-20140317173430

It is likely that Porphyric Hemophilia is the Cyrodilic strand of Vampirism, while Sanguinare Vampiris is the Skyrim strand. The game heavily hints at the idea of seperate types of Vampirism, along with seperate clans.