My mother is now infected by the strain worms so she is now a strigoi, she has in her now the Strain worms. The vector for vampirism is a small, needle-thin capillary worm known as the Strain worms, which, once introduced into the human host's bloodstream (either through a vampire's feeding or direct invasion by the worm through a wound or orifice), introduces an incurable and fast-acting virus directly into the host’s body. By manipulating the host's genes, the virus causes a human to undergo numerous, radical physical changes that slowly but inevitably transform them into a mature Strigoi vampire.

The first and most distinct vampire adaptation is the development of a long, retractable proboscis that hides beneath what was originally the host's tongue, capable of extending up to six feet from the mouth. This "stinger" is both the vampire's feeding and reproductive mechanism, shooting forth to latch onto vulnerable human prey at the throat or thigh, draining the victim's blood for nutrition and infecting the human with capillary worms at the same time, leaving every victim as a newborn, though still outwardly human, Vampire.

The vampire's jaw is set at a lower hinge than a human, the mouth gaping like a snake's when the stinger is deployed. As the structure of the stinger is modified tissue from the human lungs and throat, vampires are incapable of physical speech once the stinger had been deployed; beforehand, grunts and rudimentary monosyllabic speech are still possible (words like mom, dad, love, help, cold etc.)

A vampire's physical appearance is governed mainly by the host prior to infection. The virus first sheds those human traits that are obsolete to the Strigoi life cycle; Hair and fingernails are gradually lost, while the external nose and ears atrophy, leaving a fully matured vampire's skin as smooth and featureless as marble. The vampire's complexion is extremely pale between feedings, but appears a flushed red following a recent blood-meal. Eye coloration consists of a black pupil surrounded by a red sclera, with a white nictitating membrane sliding across for protection. Curiously, despite losing appendages and organs that are of no use, vampires develop sharp fangs that replace their original teeth, these fangs would be redundant as their primary feeding method is through the use of their stinger.

The middle fingers of both hands grow and strengthen, and a thick talon develops in place of the lost fingernail. However, at least one vampire seems to lack the thick middle talon and indeed the rest of the claws despite being a Strigoi for over fifty years. As vampire reproduction is achieved through viral infection of hosts and not through any sexual mechanism, the human genitalia also atrophy, leaving a mature vampire with no discernible sex.

The digestive and circulatory systems of a vampire are simplified and fused into a single vast, interconnected system. The interior organs come to resemble a series of connected sacs rather than anything one might expect to find. Nutrition from blood feeding is transported throughout this system via a thick, viscous white fluid that forms the vampiric equivalent of blood. This white fluid, simply referred to as "the white", has very potent healing properties if administered orally to humans and can even extend a human lifespan over time. However, in doing so one must be careful as not to ingest the worms, or else they run the risk of becoming infected. The capillary worms are present in this fluid, swimming throughout the circulatory system, often visible beneath the vampire's thin skin.

Like rodents, a vampire is unable to vomit, its suction-based digestive process functioning only one way. However, some vampires such as The Master have been able to regurgitate the worms from their bodies in order to possess another host body. All bodily waste is excreted from a single rectal orifice in the form of a pungent ammonia-based spray; a vampire will excrete for the entire duration of a feeding, purging old food as it consumes new blood.