How vampire lore emerged from shadowy medical mysteries

From "Dracula" to "True Blood," vampires are a spooky story staple that just won't die. Elements of science and medicine are also woven throughout vampire mythology, which once served as an explanation for frightening phenomena that mystified people for the bulk of human history.

Though cultures across the globe have different names for mythical undead monsters that feast on the blood of the living, it took a collision of new empirical research tools and Eastern European folklore to create our modern concept of vampires, said Nick Groom, author of "The Vampire: A New History."

READ MORE: How Dracula draws on our biggest health fears

Scientific and medical investigation in the 18th century helped "crystallize what vampires are, and what they aren't," added Groom, a professor of literature in English at the University of Macau. From there, the concept of the vampire took flight in the Western — and eventually global — zeitgeist. But it didn't happen overnight.

"The earliest reference we have to [a] vampire is from a text in Old Russian, written in 1047 A.D.," said Stanley Stepanic, an assistant professor in the department of Slavic languages and literature at the University of Virginia.

The actual term "vampire" made its written debut in 1725, Groom said. Around that time, the ruling class of the Habsburg Empire — controlled by the German royal family, whose capital was Vienna, Austria — were hearing alarming stories coming out of borderlands that they'd recently annexed from the Ottoman Empire farther east.

"In the 1720s, the military is sent in to investigate what's going on," Groom said. "And in 1725, there's a report sent back [saying] that a body has been exhumed and staked and then cremated because it was terrorizing the local community."

Over the next decade, Groom noted, fascination with the concept of vampires spread across Europe. Interdisciplinary teams of military officials, medical officers, magistrates, theologians and philosophers carried out investigations into claims of vampiric activity, exercising Enlightenment-era reasoning.

READ MORE: The scary thing about evil laughs

By the mid-18th century, a report from the Austrian empress's personal physician determined the existence of vampires to be a medical impossibility, and disparaged the Slavic communities whose folklore had long considered them a real threat, Stepanic said.

"The vampire was primarily a symbol of the things they didn't understand," he said, which to a large degree meant disease.

Here are potential medical explanations for some common vampire tropes, and how their meaning has evolved with changing times.

Disease

A handful of diseases have been connected to vampire folklore, though scholars note it's impossible to be sure of just how influential they were in shaping the mythology. Stepanic noted that pellagra, a dietary deficiency that can result from corn-heavy diets, can cause extreme skin sensitivity to sunlight.

But pellagra wasn't a problem in Eastern Europe until there was trading infrastructure to bring corn over from the Americas. Being a relatively new condition to the region during the "vampire epidemic," it would have been more likely to confirm preexisting beliefs rather than creating the lore in the first place, Stepanic said. He noted, though, that it's possible that pellagra contributed to the classic vampire symptom of bad breath.

"Those are the kind of things you can't really fully track because no one wrote down, 'In the year 1725, we decided vampires have bad breath,'" he said. "[Each symptom] just gets in there at some point."

READ MORE: Louis Pasteur's risky move to save a boy from almost certain death

Scholars think people also used vampiric traits to explain rabies, with its dramatic and ultimately lethal symptoms, including insomnia and aversions to light and water. Stepanic noted there was a rabies outbreak in Europe during the 18th century, in the middle of this particular bout of vampire hysteria.

Rabies symptoms are also associated with lycanthropy, or werewolf folklore, Jessica Wang, a professor in the departments of history and geography at the University of British Columbia, told the PBS NewsHour via email. She noted that rabies is particularly terrifying because victims experience loss of bodily control, leading to associations with animality — a connection underscored by the fact that the virus is transmitted by animal bites.

"The well-known connection between canine bites and rabies dating back to antiquity, European peasants' fears of wolves in the early modern period, and the disease's attack on human self-control together produce suggestive overtones with werewolf mythology," Wang said."

Death

Many natural processes that occur when dead bodies decompose could have been misperceived as grisly evidence of vampires, according to Stepanic.

Pressure that builds up during decomposition can "push the blood of the corpse into its mouth," he said, creating the impression of a creature that drinks blood.

READ MORE: The science of fright and why we love to be scared

Other visual descriptions traditionally associated with vampires — from a bloated appearance to shedding skin — are also hallmarks of what happens to corpses after death, Stepanic said.

When people wanted to stop a perceived vampire from attacking the living, they dug up corpses and took gruesome measures like staking or beheading the body to put it to rest, at which point they would've observed signs of decomposition.

Modern fears and reflections

Debunking the real-life existence of vampires didn't kill their appeal. Groom said this specimen of ancient folklore was swiftly poached and transformed by Western culture in places like Germany and England.

In the 19th century, vampires appeared in poetry and literature, as well as in political and economic writings from figures like Karl Marx. Several popular tales contained thinly veiled class commentary through the lens of the vampire.

Dracula, Groom noted, was a real estate investor who was well-versed in shipping infrastructure. Stepanic pointed to Byronic heroes like Lord Ruthven, a high-society man whose manipulative, toxic nature made him both literally and figuratively a monster.

Groom considers the vampire a kind of thought experiment that professionals across disciplines used to reflect on their moment in history and "understand things like the spread of infection or capitalist exploitation in different ways," he said.

Over the course of centuries and retellings of the myth, vampires have been transformed from a symbol of death and disease to different archetypes that can be seen as elegant and seductive, Stepanic said. Vampires serve as a kind of mirror of human existence, he noted, one that helps us make sense of modern issues and anxieties.

READ MORE: The 5 classic horror films you need to watch this Halloween

These creatures have been used also in more recent decades to pose questions about what it means to be an outsider or to struggle with identity, Groom said, or even characterize toxic interpersonal relationships that "drain" one party of energy and emotion.

The vampire continues to stalk our imaginations because it offers a lens to examine the big, complex questions we face as humans.

"There are so many different sorts of vampires now. And in fact, there always have been, since the 1720s," Groom said. "It's a very diverse figure and for that reason, it presents not a single mirror, but many, many different reflections that we can use in our thinking."