All vampires are born human. Vampirism is the result of a mutated viral infection which is theorized to have origins within the faerie genome. In most cases, exposure means the human's death, but over time the strongest began surviving. When the strange virus didn't kill them, their bodies were changed so dramatically that they could hardly be called human. It resulted in heightened senses, though not just hearing or scent, which are especially super-human. The sense of touch is heightened, making both pain and pleasure more intense. The world around them appears brighter with their new-found eyes. However, this is a double-edged sword. Young vampires have difficultly tolerating prolonged exposure to the sun. Only a few hours in daylight results in partial and temporary blindness and what can only be described as extreme sunburn. As a vampire gets older, and therefore stronger, this affect is lessened. After a few hundred years, the sun is hardly a hindrance at all. On the same page, they tend to be very susceptible to fire. The only ways to kill a vampire are decapitation, complete incineration, and inexplicably a stake through the heart made of either iron or wood. The wood is theorized to react in such a way that the viral cells start a self-destructive process. Iron, however, is the direct link to the virus’ fae origins.
The virus is passed as a blood-borne pathogen, much like HIV and types B and C hepatitis. Subsequently, it is passed in much the same ways as these diseases. Blood to blood, saliva to blood, sexual intercourse and IV needles can cause the upstart of the infection. Once the virus has entered the blood stream it is impossible to cure through medical means, although it is possible through a set of risky magical procedures. Once the infected pass the point in which death would occur, the virus then turns toward transforming the body. The muscle fibers increase, which eventually lead to enhanced speed and strength, and the heart begins to slow until it nearly stops. Doctors in earlier times would even mark such patient as dead, and a funeral would be held. The virus, which remains in the vampire's blood stream, feeds on the red blood cells and hemoglobin within its host. This is the reason for the vampire thirst. If the infected went a prolonged period without feeding it would result in their death once their own body's supply had run out. In direct link to the changes in their bodies, vampires are rendered infertile.
