Do Vampires Visit Other Neighborhoods Autonomously?

I have been playing since vampires came out and tonight was the first time I had any real problem with vampires other than little annoyances like vampires being bar tenders in one save and not being able to send my sim home or quit the game to go to bed because a vampire is visiting the lot. Vlad has come to my sims door and then eventually left in some of my saves in others there has been no sign of him. Tonight he just walked in and attacked my sim so of course he had a horrible day at work after that. Vlad has now been deleted from this save and will be deleted from all other games before I play. I don't know what was different this time. My sims are always talking about vampires, it's kind of hard to shut them up, so I don't think that was it. The only other thing I can think may have happened was that a visiting sim may have been looking up vampire information on the computer. Any way all's well now I think. They survived anyway.