Found this other related"VAMPIRE" article,Once considered demon possession, Vampirism is now registered by the United States Health Department, alongside Werewolves, as a disease. Transmitted only through blood transfusion, Vampirism is essentially a virus.
There is a short incubation period characterized by unnaturally fast recovery from wounds, enhanced sight at night and an aversion to sunlight. After this incubation period (which can last anywhere from 24 hours to years), the user will enter the primary stage, in which signs similar to Rabies are produced—a tendency to attack those around them and an urge to draw and consume blood. If any blood save for that of the infected is consumed, survivability drops to 3%., due to the fact that the body has yet to stabilize. If none is consumed, though, mortality drops to around 82%. The other 18% become permanent carriers, what we call Vampires.
A Vampire’s infected body cannot produce Protein and many blood cells, and thus it is forced to absorb this through the blood of others. A Vampire’s body then condenses the blood into a superconcentrated form, leading to Vampire blood becoming distinctly dark colored, almost black.
A Vampire who consumes human blood will be endlessly capable of dividing and recovering his already-existent cells, though the loss of transmittable genetic code means that he/she will never grow. Animal blood, because its composition and genetic codes are distinctly different from that of a human, will yield a far lower energy intake and will cause the vampire to “age,” in fact slowly wasting away.
The Vampire’s body must maintain the protein it has, and thus it will dispense of unneeded functions when it is not used. For this reason, evolution has wired the Average Vampire’s mind to stay away from sunlight, since the presence of UV rays forces the Vampire body to produce melanin and pigments, something that is extremely draining for the Vampire in question.
A vampire can consume food, but the need to activate his digestive system is also very tiring. Vampiric Cells tend to react badly to metals, particularly silver. While they can touch it, dissolution into the body is extremely damaging. Because, unlike demon possession, Vampirism is more an organic condition than a curse, normally effective exorcism methods such as Holy Water, Prayer Chants and Purification salt have very little effect.
In that 18% window of infected Vampires, about one in nine infected vampires enters an intermediate stage. In a small fraction of these cases, the body is strong enough to completely reject the Vampirism Virus and revert the body to human (though there are lingering symptoms, such as a fast recovery rate and/or a fear of light).
In some cases, while vampiric, the victim retains some human traits. In the majority of cases, though, the body’s regular immune system and the Vampiric blood injected enters a stalemate in which the body gains an immunity to vampirism, but no normal symptoms or abilities of Vampirism.
Sometimes, though, when the body senses it is in danger or is badly weakened, the vampire blood temporarily activates, allowing the individual to escape the given situation and temporarily gain the abilities the individual needs to survive.
Vampires naturally align themselves into groups, called “Clans.” Usually, the basis for the formation of these Clans is around one specific individual.
Because Vampire blood weakens with each generation that it is spread down (With the exception of a Transmission, when a Vampire transmits all its blood to another individual as a successor.), this specific Individual is usually the founder. Even so, the current Vampires are far weaker both magically and in a flesh-and-blood sense in comparison to their ancestors.
While most Vampire Clans are First Generation, some are passed down through successors. In respect to the progress of the Vampirism Virus, the strongest Clans are Eastern European (the Jiang Shi and Oni clans of Asia are completely different).
Of the four founding clans of the Vampires, only the Wallachian house remains intact, and greatly weakened. Vampires once worked for the United States CDC, but some served anything from the Church to local Mafias.