Pitch idea for an idea for a new horror movie

A man aged about 46 named Frank Spellman is a loner who has, for some reason or another (perhaps he was abused) is a horrible person and takes part in illegal activities involving sexual abuse and murder. However, from doing so he contracts H.I.V, and because he is evil, starts to inject people in busy places (like nightclubs) with his blood. A woman who works in a particular club he goes to had been watching him and his actions for a while, rightly suspicious of him. When she discovers what he's doing, she attempts to stop him, but in doing so becomes his victim. He tries to kill her but she becomes the final girl and eventually overcomes him. "Dun dun dunnnn!"