Vampire Origin Story: How a Real Virus Inspired the Halloween Legend |Kathleen McAuliffe | Big Think
One parasitic manipulation, and perhaps the oldest one known on the books, is what the rabies virus does. As everyone knows, once a rabid animal bites you, the virus can then travel to the brain. And what it does is it invades the hypothalamus, which is the center of the brain that controls all our most fundamental drives, for example, anger and aggression, hunger and your sex drive.
And it's not commonly known, but an atypical symptom of rabies is hypersexuality. People who become infected can occasionally just develop this voracious appetite for sex. There are a number of scientists who think that the vampire legend actually is based on rabies, that it's rabies that was the inspiration for it, because as we know, for example, vampires are hypersexual.
Another aspect of rabies in people is that it makes people very sensitive to any kind of stimuli. So, for example, even the lightest breeze can make somebody agitated. People with rabies also hate strong light; it really bothers them. For reasons no one understands, they become hydrophobic, which is to say they are tormented by the sight of water or hearing water splashing in a basin.
If you think about the vampire legend, vampires hate light; that's why they're nocturnal. In the 18th century, when a lot of vampire legends swept Eastern Europe, it was thought that pouring water around the grave of a person would keep them from rising at night and becoming a vampire. Also, in Eastern Europe at that time, it was believed—and these weren't just legends—that this was a true risk. It was thought that some people could rise from their beds at night and then assume the form of a dog or wolf and attack people or rape people.
So you can see how vampirism may be, in some ways, inspired by what rabies does to people. Of course, vampires are more likely to assume the form of dogs, which we know can be one vector of rabies, but also bats, which can spread rabies. And then finally, this is an interesting link: it typically takes about 40 days from the time a person is bitten by a rabid animal until their death, and vampires, according to legend, lived 40 days.