I think Dr. Tofu should have said a little early on that he thought it was
a vampire.  It's not as if a group of people who've run into magical curses
and even gods would think it's as strange as the characters in Dracula would
think it is.  (and when they were finally told, they didn't think it's that
strange).  Not telling anyone struck me more as a contrivance than anything
else; it let the characters go around without taking proper precautions or
being alert.