Med school is all about learning new things -- but not all of these new things are all that interesting. If more lecturers paid attention to the times, maybe people would tune in more.
In a constant quest for case-relevance, I tune in to the hubbub that surrounds me... Halloween! I got the idea from Dr. Charles' elf entry and from Yahoo story about a paper entitled "Ghosts, Zombies and Vampires - Cinema fiction versus Physics Reality" by Costas Efthhimiou. They've got some great stories and I wanted to add a bit more. It might not be PC, it might not even wholly accurate, but gosh darnit, I hope it's educational and dare I say it?!? I hope it's amusing as well.
To start things off in my investigation into occult medical "mythdiagnoses", I turn to the classic Halloween monster of them all:
Vampires are photophobes and hemophiles, fearing sunlight but loving blood. This makes them the perfect candidates for porphyria! (wikipedia, lifespan) Porphyria is a group of genetic defects in heme synthesis. Accumulation of various intermediate products give rise to various symptoms like tea or wine-colored urine, neurological problems and photosensitivity.
My biochem professor speculated that King (correction: George) the III had a few bouts of acute intermittent porphyria and as a result, Britain lost in the American Revolution. People with other types of porphyria with buildups of tetrapyrrole get itchy or burning sensations in their skin in bright light. This can lead to hair loss, loosening of nail beds and retraction of gum lines (which is probably less disconcerting around Halloween.)
In all fairness, I have a link for the skeptics (straight dope.)
Vampires are said to have a strong aversion to garlic and with a little research, I learned that garlic does have an effect on blood. Ancient Babylonia and China used garlic for medicinal purposes and it is now believed that allicin is the active ingredient. Raw crushed garlic has the highest concentration of antiplatelet (platelet aggregation occurs before a fibrin clot forms and coagulates) and fibrinolytic properties.
A few types of porphyria (variegate and cutanea tarda) can cause hypertrichosis (wikipedia) or excessive hair growth... so these might have contributed to werewolf legends as well.
Since the phenotype is so readily apparent, it was much easier to find information about people with hypertrichosis vs porphyria. Hirsutism (wikipedia) is another type of excessive hair growth usually referring to women with high androgen production.
Familial hypertrichosis is not a myth. People with these X-linked conditions are often male, performing in circus shows. ABC news did a story on one such man a few months ago, entitled "Real-Life Werewolves," about a Mr. Gomez who is a 5th generation wolfman! Chuy the wolfboy also has an interview online and oddly enough, they are both men in mexican circus shows. They have interesting stories to tell.
It doesn't seem like they have any predisposition to howl at the moon or turn violent, but animals do bite more during a full moon. (BMJ, 2000.)
Is there a basis for killing werewolves with a silver bullet? None that I could find. Perhaps it is a Type I contact allergy to silver... copper or nickel is more common (I think.) Perhaps it has to do with the antimicrobial activity of something like silver nitrate...
The Efthimiou paper I mention earlier has a compelling argument about the basis of zombie legends. Basically, Haitian voodoo priests use pufferfish tetradotoxin to paralyze victims and make them appear to be dead. When(If!) the toxin wears off, the subject awakens as if from the dead.
This is all well and good, but it doesn't quite match up to today's image of zombies as hungry, mindless monsters with rotting flesh. People suffering from lepromatous leprosy (WHO) match the physical description surprisingly well. They have an infection of Mycobacterium leprae and their immune systems have taken the wrong approach to getting rid of it. Leprosy affects the skin and nerves.
Peripheral neuropathy in places like the sural nerve (in the shin of the leg) causes the foot to drag on the ground, making them lift their legs higher to compensate. Damage to the radial nerve (though rare in leprosy patients) causes wrist drop.
Decreased sensation of these floppy feet and numb hands means that damage to them goes unnoticed. Toe and finger stubbing can lead to necrosis, as these tissues literally rot and fall off their body.
Zombies are not as much of a threat to medieval peasants as werewolves and vampires were, so I can't really think of any myths about how to kill them (other than decapitation, but that's not very subtle.) Oh! Mycobacterium are acid-fast bacteria. Holy water... acid... ok, it's a stretch.
I am not quite so convinced by Efthhimiou's arguments against vampires simply refuting it by demonstrating the implausability of exponential vampire growth assumes a 100% transmissibility rate which... ironically.... I find implausible! ;-) and ghosts, which he chalks up to temperature gradient differences and psychological expectations. Where's the weird phenomena in that explanation?
Vic Tandy, an engineer, started working at a "haunted" lab in Coventry, England. Everyone had feelings of being watched and a lot of people were thoroughly creeped out. This engineer was working late one night and he saw a grey figure approach him at one point. "It would not be unreasonable to suggest that I was terrified," he says. The next day, he noticed that a fencing foil he was working on was vibrating. He was frightened at first, but after some investigation he found that his lab recently had installed an extractor fan.
This fan created a standing air wave projecting infrasound (wikipedia) at 19 Hz. This sound is not heard by human ears, but we can still perceive it as symptoms of uneasiness, dizziness and shortness of breath.
According to NASA, the human eyeball has a resonance of 18 Hz. In the standing airwave, the vibrating eyeball can cause a "smearing of vision". Hyperventilation is another symptom of whole body vibration. I've noticed that this sort of lightheadedness gives objects a special glow or aura afterward.
Interestingly, Tandy goes on to find 19 Hz infrasound again in a 14th century cellar in the Tourist Information Centre of Coventry.
So, never let it be said that the myths are all fictitious stories... there is a level of fact and fun can be had in finding it!