Did vampires suffer from the disease porphyria — or not?
A few years back, in your book More of the Straight Dope, you repeated the story that vampire legends might have been based on victims of the disease porphyria, which causes disfigurement and is a result of certain blood deficiencies. This hypothesis was invented by a biochemist named David Dolphin. It doesn't hold up under scientific scrutiny, since drinking blood doesn't actually bring victims any relief, nor do victims crave blood since they don't intuitively know they have a blood deficiency (it was not known that that caused the disease until relatively recently). However, the story has become very popular and has caused untold suffering for victims of porphyria, who have been branded "vampires" and taunted because of it. You might want to address this in your column when you've got the time.
I could try to weasel on this one, but I may as well 'fess up. I failed to check out this story before sticking it in my book. (Hey, the guy was making a speech to a scientific society! It was reported in the New York Times!) As a result I was taken in by an explanation that was superficially plausible but on examination turned out to be complete crap.
In 1985 biochemist David Dolphin proposed that the vampires of folklore may actually have been people suffering from porphyria, a group of rare, largely hereditary blood diseases. According to the Times account of his remarks:
(1) 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.
(2) To avoid sunlight, people with serious cases of porphyria go out only at night, just like Dracula.
(3) Today porphyria can be treated with injections of blood products. Centuries ago, porphyria victims might have sought to treat themselves by drinking blood.
(4) 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.
(5) Garlic contains a chemical that worsens porphyria symptoms, causing sufferers to avoid it. Just like vampires.
Great story, eh? The media, including me, went nuts, and today everybody "knows" that porphyria patients are vampires — to the distress of people who actually have these diseases.
Just one problem. People with porphyria aren't vampires, and there's no reason to think that the vampires of folklore had the disease (or existed at all). To respond point by point:
(1) Porphyria comprises seven separate disorders. Skin problems are a fairly common symptom, but only the rarest form — congenital erythropoietic porphyria — causes severe disfigurement. Just 200 cases of this disease have been diagnosed, surely too few to account for the widespread belief in vampires. In any case, alleged vampires exhumed in the 18th century typically weren't disfigured but appeared as they had in life (except for being dead, of course).
(2) The idea that vampires abhor sunlight was an invention of fiction writers. In Europe during the 18th and 19th centuries, vampires were sometimes reported to have been sighted during the day. Bram Stoker's Dracula was deathly pale, but folkloric vampires, in the Balkans anyway, were said to be ruddy-faced due to blood consumption.
(3) Porphyria victims don't crave blood. Drinking blood will not alleviate their symptoms, nor has there ever been a general belief that it would. The blood chemicals porphyria victims need do not survive digestion.
(4) In light of the preceding, the scenario described in point #4 above is unlikely.
(5) No one has proved that garlic worsens porphyria.
Professor Dolphin never published a formal paper describing his theory. When I phoned, he didn't wish to speak to me and would say only that "it was just speculation" and that "I haven't worked in this area for many years."
The practice of trying to match diseases with well-known figures in history or folklore has a long and not entirely reputable history. (Porphyria, for one, has also been blamed for werewolves.) Maybe next time we'll know better.