Although there is evidence of vampire-like attacks on humans and other animals, there is no proof that vampires are real. Further, with advances in DNA testing and other forensics, it’s unlikely that actual vampires or people infected with a vampire “virus” could go undetected.
Vampire myths originate from many sources. For instance, as etiologies, they explain sexual misconduct, rabies outbreaks and isolated incidents of cannibalism. According to “Vampires: Fact, Fiction and Folklore,” vampires myths have also arisen from a poor understanding of the process of decomposition, during which dead bodies can move and even sit up; the skin also markedly changes texture as well as color, and abdominal bloating can force blood up out of the mouth.
On a more practical level, local officials probably used stories about marauding vampires to impose curfews during disease outbreaks, when bandits were afoot, or during a similar crisis. Moreover, folk worried about being stalked by the undead pay less attention to other unacceptable behavior that might result in bite wounds, including cheating husbands, wayward daughters, or corrupt and diabolical servants and rulers. It’s also true that real tropical and other diseases mimic conditions and symptoms of vampirism. That people still tease themselves with the reality of vampires suggests that forensic science can’t yet explain away all of the myths.