Halloween Week Day 2: Vampires
Here is another interesting fact from Stephen James O'Meara, author of Are You Afraid Yet?: The Science Behind Scary Stuff:
People who used to be labeled as "vampires" probably had a horrible blood disease called Porphyria. Victims tend to have very photosensitive skin so when they get exposed to the sun, their skin boils and blisters. As a result, they often only leave home at night.
Also, the disease turns their teeth red, so it looks like they've been biting necks, and their urine is a purplish red, so they appear to have drank blood. It didn't help that early doctors recommended that the patients drink blood from slaughterhouses to treat the condition!
According to O'Meara, it is likely that Bram Stoker got his idea for vampires by studying people with Porphyria.
On a side note, if blood-seeking vampires did exist, garlic would prevent their attacks. Garlic does a nice job of covering up the scent of blood. Helpful hint: keep some garlic around in the summertime to ward off mosquitoes!