there was once in a book, i read about how the idea of vampirism came about
i only remember vaguely anyway
it was said that, at that time, sometimes people lost consciousness, and due to the lack of medical knowledge, they were often written off as dead and buried unknowingly alive. after a while, the victim wakes up, tries to claw himself out of the grave, while biting on his own arm, due to hunger and whatever la
so that could contribute to the idea of vamps.
also there are deseases which makes people look really pale, pigment stuff.. or make them adverse to sunlight.
thats what the book said anyway. some guide to the supernatural. coolest supernatural guidebook i've read.