This sounds very much like The Mindworm, a short story by C.M. Kornbluth.
The protagonist is an orphan who feeds by draining mental activity from others, killing them in the process. He moves from town to town, eavesdropping on people's thoughts, and feeding on them as a kind of psychic vampire. Eventually he arrives in a town largely populated by eastern Europeans who still maintain memories of dealing with such vampires from thousands of years ago. There he kills a young girl, but unlike his previous kills he is observed in the act:
The countless eyes of the other town, with more than two thousand
years of experience in such things, had been following him. What he
had sensed as a meaningless hash of noise was actually an impassioned
outburst in a nearby darkened house.
"Fools! fools! Now he has taken a virgin! I said not to wait. What
will we say to her mother?"
An old man with handlebar mustache and, in spite of the heat, his
shirt sleeves decently rolled down and buttoned at the cuffs, evenly
replied: "My heart in me died with hers, Casimir, but one must be
sure. It would be a terrible thing to make a mistake in such an
affair."
The townspeople make their minds unreadable, and move in to kill him in the old-fashioned way:
The Mindworm strolled back to his hotel and napped on the made bed
briefly. A tingle of danger awakened him. Instantly he cast out:
"... gobblegobble whompyear."
"... whampyir."
"WAMPYIR!"
Close! Close and deadly!
The door of his room burst open, and mustached old men with their
shirt sleeves rolled down and decently buttoned at the cuffs
unhesitatingly marched in, their thoughts a turmoil of alien noises,
foreign gibberish that he could not wrap his mind around,
disconcerting, from every direction.
The sharpened stake was through his heart and the scythe blade through
his throat before he could realize that he had not been the first of
his kind; and that what clever people have not yet learned, some quite
ordinary people have not yet entirely forgotten.
Possibly "wampyir" is the unusual spelling you recall.
The full text of the story is available at the Gutenberg project.