If we take a stroll down memory lane, we remember that in Morrowind's expansion pack, Bloodmoon, Solstheim was basically divided by the East Empire Company and Nords, however there was talk in Oblivion (reading this from the wiki because I never bothered with that sort of idle chit chat with NPCs) that the Nords were trying to take back the island and money had run out of the Raven Rock colony, yadda yadda, who cares. What I'm interested in is that, if Solstheim is now Nordic, wouldn't there be at least some travel between Skyrim and Solstheim leading to a spread of the disease/curse?