Premature burial

Vampire legends may have also been influenced by individuals being buried alive because of shortcomings in the medical knowledge of the time. In some cases in which people reported sounds emanating from a specific coffin, it was later dug up and fingernail marks were discovered on the inside from the victim trying to escape. In other cases the person would hit their heads, noses or faces and it would appear that they had been "feeding". A problem with this theory is the question of how people presumably buried alive managed to stay alive for any extended period without food, water or fresh air. An alternate explanation for noise is the bubbling of escaping gases from natural decomposition of bodies. Another likely cause of disordered tombs is grave robbery.

Disease

Folkloric vampirism has been associated with clusters of deaths from unidentifiable or mysterious illnesses, usually within the same family or the same small community. The epidemic allusion is obvious in the classical cases of Petar Blagojevich and Arnold Paole, and even more so in the case of Mercy Brown and in the vampire beliefs of New England generally, where a specific disease, tuberculosis, was associated with outbreaks of vampirism. As with the pneumonic form of bubonic plague, it was associated with breakdown of lung tissue which would cause blood to appear at the lips.

In 1985, biochemist David Dolphin proposed a link between the rare blood disorder porphyria and vampire folklore. Noting that the condition is treated by intravenous haem, he suggested that the consumption of large amounts of blood may result in haem being transported somehow across the stomach wall and into the bloodstream. Thus vampires were merely sufferers of porphyria seeking to replace haem and alleviate their symptoms.

The theory has been rebuffed medically as suggestions that porphyria sufferers crave the haem in human blood, or that the consumption of blood might ease the symptoms of porphyria, are based on a misunderstanding of the disease. Furthermore, Dolphin was noted to have confused fictional (bloodsucking) vampires with those of folklore, many of whom were not noted to drink blood. Similarly, a parallel is made between sensitivity to sunlight by sufferers, yet this was associated with fictional and not folkloric vampires. In any case, Dolphin did not go on to publish his work more widely. Despite being dismissed by experts, the link gained media attention and entered popular modern folklore.

Juan Gómez-Alonso, a neurologist, examined the possible link of rabies with vampire folklore. The susceptibility to garlic and light could be due to hypersensitivity, which is a symptom of rabies. It can also affect portions of the brain that could lead to disturbance of normal sleep patterns (thus becoming nocturnal) and hypersexuality. Legend once said a man was not rabid if he could look at his own reflection (an allusion to the legend that vampires have no reflection). Wolves and bats, which are often associated with vampires, can be carriers of rabies. The disease can also lead to a drive to bite others and to a bloody frothing at the mouth.

Psychodynamic theories

In his 1931 treatise On the Nightmare, Welsh psychoanalyst Ernest Jones asserted that vampires are symbolic of several unconscious drives and defence mechanisms. Emotions such as love, guilt, and hate fuel the idea of the return of the dead to the grave. Desiring a reunion with loved ones, mourners may project the idea that the recently dead must in return yearn the same. From this arises the belief that folkloric vampires and revenants visit relatives, particularly their spouses, first.

In cases where there was unconscious guilt associated with the relationship, the wish for reunion may be subverted by anxiety. This may lead to repression, which Sigmund Freud had linked with the development of morbid dread. Jones surmised in this case the original wish of a (sexual) reunion may be drastically changed: desire is replaced by fear; love is replaced by sadism, and the object or loved one is replaced by an unknown entity. The sexual aspect may or may not be present. Some modern critics have proposed a simpler theory: People identify with immortal vampires because, by so doing, they overcome, or at least temporarily escape from, their fear of dying.

Jones linked the innate sexuality of bloodsucking with cannibalism, with a folkloric connection with incubus-like behaviour. He added that when more normal aspects of sexuality are repressed, regressed forms may be expressed, in particular sadism; he felt that oral sadism is integral in vampiric behaviour.

Political interpretations

The reinvention of the vampire myth in the modern era is not without political overtones. The aristocratic Count Dracula, alone in his castle apart from a few demented retainers, appearing only at night to feed on his peasantry, is symbolic of the parasitic ancien régime. In his entry for "Vampires" in the Dictionnaire philosophique (1764), Voltaire notices how the mid-18th century coincided with the decline of the folkloric belief in the existence of vampires but that now "there were stock-jobbers, brokers, and men of business, who sucked the blood of the people in broad daylight; but they were not dead, though corrupted. These true suckers lived not in cemeteries, but in very agreeable palaces".

Marx defined capital as "dead labour which, vampire-like, lives only by sucking living labour, and lives the more, the more labour it sucks". Werner Herzog, in his Nosferatu the Vampyre, gives this political interpretation an extra ironic twist when protagonist Jonathan Harker, a middle-class solicitor, becomes the next vampire; in this way the capitalist bourgeois becomes the next parasitic class.