It’s widely known that King George III was crazy as a loon. His bouts of madness are legendary: between 1780 and 1820 he suffered five serious breakdowns, during which he was known to hold hours-long conversations with trees and clouds and was considered dangerous enough to spend years locked in Windsor Castle’s padded rooms. One popular theory is that he may have suffered from the blood disease porphyria (the effects of which were exacerbated by the arsenic-based powder in his powdered wig), which can cause intense paranoia and hallucinations.

Porphyria has also been called “the vampire disease,” and according to popular legend, is the reason we have vampire stories at all. In 1985 a (now somewhat debunked but then widely touted) expert proposed the following:

• Porphyria victims are extraordinarily sensitive to sunlight. Even mild exposure can cause severe disfigurement. Facial skin may scar, the nose and fingers may fall off, and the lips and gums may become so taut that the teeth project like fangs.
• To avoid sunlight, people with serious cases of porphyria go out only at night, just like Dracula.
• Today porphyria can be treated with injections of blood products. Centuries ago, porphyria victims might have sought to treat themselves by drinking blood.
• Porphyria is inherited, but the symptoms may not manifest themselves until brought on by stress. Suppose a sibling with an active case of the disease bites you to quench his thirst for blood. Très stressful, non? Suddenly your own latent porphyria goes critical and you start growing fangs too.
• Garlic contains a chemical that worsens porphyria symptoms, causing sufferers to avoid it. Just like vampires.

Unfortunately — because it would’ve been a really cool story — much of this was proven to be false: garlic has no effect on porphyria, for instance, and blood ingested through the stomach does nothing to alleviate the disease’s symptoms.

But just because it looks like there’s no logical, medical explanation for vampirism doesn’t stop people from jumping to conclusions — about their heads of state. During late 2002 and early 2003, hysteria about alleged attacks of vampires swept through the African country of Malawi. Mobs stoned one individual to death and attacked at least four others, including Governor Eric Chiwaya, based on the belief that the government was colluding with vampires.