I realize that he can't just tell a bunch of 19th century Englishmen that she's being attacked by a magical blood-sucking shape-shifting monster and expect to be believed, but perhaps there is a middle ground between VAMPIRE and I'M NOT TELLING YOU ANYTHING. What if he started by saying "vampire bat, which we must hunt down using these special silver bullets"? A blood-sucking animal might be an easier pill to swallow.