Victims of vampire attacks in 19th-century novels didn't just turn pale, swoon and waste away; they displayed a wide range of symptoms that hinted at deadly attacks by a fanged, bloodsucking predator.

However, the descriptions of those symptoms were likely grounded in observations of real medical conditions. In fact, the hallmarks of a so-called vampire attack strongly resemble physical symptoms caused by cases of acute leukemia, according to a new study.

At the time, leukemia had not yet been identified as a disease among the medical community. Perhaps this is why its particular array of symptoms, the cause of which was then unknown, inspired writers to assign a supernatural explanation, researchers recently reported.

Related: 7 Strange Ways Humans Act Like Vampires

Leukemia is a type of cancer that affects white blood cells. It originates in bone marrow; the cancer cells quickly multiply and overwhelm the production and activity of normal white blood cells, leading to anemia and vulnerability to infections. In acute leukemia, the disease progresses very quickly if untreated, according to the National Cancer Institute.

For their blood-chilling study, the researchers looked to three novels that formed the foundation of the popular vampire genre: "The Vampyre" by John William Polidori (1819), "Carmilla" by J. Sheridan Le Fanu (1879) and "Dracula" by Bram Stoker (1897). The scientists documented all characters that were identified as vampire victims, compiling a list of symptoms and the length of time those symptoms lasted. Then, the researchers compared the symptoms with those produced by a range of illnesses.

"The Vampyre" portrayed just two victims, describing no symptoms leading up to their deaths. "Carmilla" had three victims, all female; they displayed "persistent exhaustion, fever, pallor, dyspnoea [difficulty breathing] and chest pain," as well as red marks on the skin of their chests, the scientists reported.

Published more than a decade after "Carmilla," "Dracula" was brimming with even more details of the ailments plaguing the novel's three vampire victims, one of whom — Lucy Westenra — eventually died (and then revived as a vampire). Each of the victims suffered from "malaise, paleness, fatigue, anorexia, dyspnoea and weight loss," accompanied by a trance-like, delirious state, according to the study.

'Bloodless, but not anemic'

Some of those symptoms could be explained by other diseases, such as tuberculosis (TB), a bacterial lung infection. However, TB was a well-known disease by the 19th century, and none of the fictional doctors in the vampire novels diagnosed their patients with TB. This suggests that there were other symptoms that didn't match what doctors would expect to see in a TB patient, the researchers wrote.

Diphtheria, a bacterial infection that affects breathing and swallowing, also produces similar symptoms to acute leukemia. But it additionally causes coughing and discolored patches around the mouth and throat, which weren't described in any of the novels.

Another possible diagnosis for a vampire victim could be anemia, a deficiency in red blood cells that can lead to fatigue and unusual pallor. Again, this condition was known to 19th-century doctors, and yet none of the doctors in the three novels suggest it for the vampire victims. In fact, Westenra in "Dracula" is described as "bloodless, but not anemic," and her symptoms overall provided "a textbook example" of a patient suffering from acute leukemia, according to the study.

"None of the other diseases considered matched as well as acute leukemia," the study authors said.

"We therefore conclude that real-life acute leukemia patients very likely were the inspiration for the symptoms of victims in the Gothic vampire literature."

The findings were published online Nov. 12 in the Irish Journal of Medical Science.

Originally published on Live Science.