Medical conditions and lack of medical knowledge throughout history have had a strong impact on vampire myths. Some of the following books provide information on possible medical reasons behind the vampire myths.
AMERICAN VAMPIRES by Norine Dresser. Penguin Books. 1989.
ISBN 0-393-02678-7
This book discusses the disease porphyria and it's symptoms which may have been behind some of the vampire myths. It also discusses the impact on people suffering from porphyria of a scientific paper by chemist Dr David Dolphin in 1985, in which he hypothesized the link between the disease and vampire myths.
It also covers tuberculosis (under it's old name consumption in the book's index). Because TB is so contagious, it was common for several members of a family to get it(especially in the old, unhygenic days when people were often poorly fed). The first person to die from the disease usually got blamed as being the vampire that was returning to prey on and weaken the others. _American Vampires discusses some cases that occurred in New England. In some of these cases the people actually dug up dead relatives, cut out and burned the hearts.
VAMPIRES, BURIAL AND DEATH by Paul Barber. Yale University Press. 1988.
ISBN 0-300-04126-8 or 0-300-04859-8
This book briefly discusses porphyria and consumption. However, it
is REALLY good at discussing the symptoms and the speed of decomposition (which can vary depending on soil temperature, moisture, acidity and other variables). A lack of understanding decomposition was probably an important factor in promoting the belief that some exhumed bodies were vampires. Features such as grown fingernails, "new" skin on hands and feet, ruddy complexion and "fresh blood" coming from mouth, nose, etc were due to decomposition, but were frequently cited as "proof" that the body was that of a vampire.
The book also discusses some customs surrounding burial that would have impacted the folklore when things went wrong. And the chapter that described French botanist De Tournfort's experience with a Greek town when they exhumed a "vampire" really puts a new light on the capabilities of people to brainwash themselves through fear.
WITCHCRAFT by William Seabright. Sphere Books. 1970.
This older book (probably out of print now) contains a discussion of
anemia, including a case history of someone with anemia who drank other people's blood
before she died of the disease.
VAMPIRES, WEREWOLVES AND DEMONS by Richard Noll. Brunner/Mazel Pub. 1992.
ISBN 0-87630-632-6
This psychiatrist has written a fascinating book, the first section of which discusses 20th century reports (along with interesting and illustrative case histories) of people who have been diagnosed as vampires. He also proposes a new definition of clinical vampirism which he names Renfield's Syndrome in honour of Bram Stoker's fly-eating maniac. The other two sections deal with equally interesting information on clinical lycanthropy and possession.
V IS FOR VAMPIRE: THE A-Z GUIDE TO EVERYTHING UNDEAD by David Skal Plume Books. 1996. ISBN 0-562-27173-8.
This is an encyclopedia like the title says, but unlike most encyclopedias, it contains a very psychological slant. Many of the topics such as Darwin, homosecuality, codependency, cannibalism, xenophobia, Freud, psychoanalysis, etc are relevant to vampires and the fascination and hold these creatures have on us today. Also, film and fiction topics in the book have psychological information where relevant.