Porphyria is a collection of genetic disorders in which the enzymes catalyzing hemoglobin production do not function correctly.
Symptoms
The symptoms are similar to those associated with Count Dracula and vampire folklore. They include sensitivity to sunlight, abdominal pains and vomiting, and purple urine, which may lead to the belief that the victim has been drinking blood. The indicators also include increased hair growth, tightened skin and the shrinkage of the gums making the canine teeth look more prominent, and general depression and morose moodiness.
The Un-dead and the Natural Decomposition Process
Centuries ago, especially during the Dark Ages, ignorance fed on wild tales of the un-dead prowling around graveyards and hiding in the shadows, seeking to find innocents and drink their blood so as to revivify themselves. There was no knowledge about the stages of decomposition of corpses and people were afraid that the dead might come back to terrorize them. Often relatives exhumed the bodies to make sure that they were still dead and this gruesome rite only increased their fear.
What they found in fresh graves led them to believe that maybe the dead weren't totally deceased. The corpse might have a red face and a bloated body. The stench was revolting due to the methane and other putrefying gases which were released into the body tissues, blowing it up like a balloon and giving it an obese appearance. The red face was due to the hemolysis breaking down the red blood cells and other skin tissues.
What appeared to be fresh skin was actually the deeper layers of skin revealed as the upper ones peeled off. Bloody fluid oozing from the mouth was due to internal pressure pushing fluids out of the lungs and esophagus as the body decayed and liquefied.
Killing the Corpse
All these signs were taken as evidence that the corpse was still alive. Frightened villagers brought in the priests, hacked the bodies apart and drove stakes through their hearts to make sure that they were really, really dead. And so the legend of the vampire grew through the ages and around the world.
Porphyria, the Disease
But the truth is really quite mundane, as is usually the case, and it all revolves around the blood-drinking thing in the stories. It goes back to a group of diseases generally called porphyria which involves disorders in the enzymes involved in producing hemoglobin. This is the iron-containing molecule present in red blood cells that is essential in transporting oxygen throughout the body.
The "vampire disease" is genetic and not contagious. The porphyrias are a group of diseases rather than just one. There are eight steps in the metabolism of hemoglobin and if there's a mistake at any one of those steps, it's a different disease of the same type. Fortunately it can be controlled by repeated blood transfusions, but there is no cure.
List of Sources:
www:porphyriafoundation.com
www:associatedcontent.com/article/117021/porphyria_and_the_vampire_legend
Diane Evans - I am a retired civil engineer as well as a member of Sisters in Crime and the Society of Children's Book Writers and Illustrators.
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