This is a British film made in 1958. It was first released in the UK in August 1958, but saw its US debut in October of the same year. The plot of this little classic horror obscurity is that a (mad?) scientist, Dr. Callistratus, with the help of his hunchbacked assistant, Carl, is conducting experiments with the blood of criminally insane prison inmates. Turns out the Doctor has a rare "blood disease", and is thought by many to be a vampire. It's an atmospheric gothic horror/thriller with shades of Dracula AND Frankenstein. "Blood of the Vampire" looks and feels very much like a Hammer Films production, and there's a good reason for this. Hammer Films veteran, Jimmy Sangster, wrote the screenplay. Just prior to this film, Sangster wrote the screenplays to two very important Hammer films - "The Curse of Frankenstein" in 1957 and "The Horror of Dracula" in 1958. These two films, along with the Italian "I Vampiri" in 1956, would spark a "gothic horror" renaissance across the world. Soon Italy's long-dead horror market would be reinvigorated. Following Riccardo Freda's "I Vampiri", the films co-director and cinematographer, Mario Bava, would go on to helm "Black Sunday" in 1960, followed by a string of other gothic horror successes. In the USA, Roger Corman was also riding the gothic horror wave with "The Fall of the House of Usher" in 1960 followed by a slew of other Poe-related films, many of them starring Vincent Price.
Getting back to "Blood of the Vampire", it was directed by Henry Cass, and is the only horror film he directed. He also directed "The Hand" two years later, in 1960, which has some horror elements but is actually a crime thriller. Another Hammer Films connection is actress Barbara Shelley, who plays Madeleine Duval in "Blood of the Vampire". She would go on to play roles in several Hammer movies, including "The Shadow of the Cat" (1961), "The Gorgon" (1964), "Dracula: Prince of Darkness" and "Rasputin: The Mad Monk" (both 1966), and "Five Million Years to Earth" (1967). Finally, a note about the VHS release of "Blood of the Vampire". It was released in 1978 by Magnetic Video Corporation, the first distributor of VHS and Beta tapes in the USA, and it has the distinction of being the first horror movie ever released on those formats; and quite possibly the first horror movie released on any home video format (as there were a couple of short-lived home video formats before VHS and Beta, such as Cartrivision).