Vampires fear light, have pale skin, and grow fangs. Doctors believe there may be a medical explanation for the proliferation of vampire stories in Eastern Europe. Porphyria, a hereditary blood disease, was once widespread among the aristocracy. Patients were sensitive to light, developed brownish teeth, and had skin lesions. They were often told to drink blood from other people to replenish their own.
Rabies also causes vampire-like symptoms, insomnia, delirium, and strange behavior.
A rabies epidemic occurred in Transylvania around the time of Dracula , the world's most notorious vampire. In Greek myth , Lycaos was the extraordinarily cruel king of Arcadia. Lycaos sought favor with Zeus by offering him the flesh of a young child. Enraged, Zeus turned Lycaos into a wolf. The belief that certain people can turn themselves into animals, especially wolves, and roam the earth doing evil became widespread.