For the purpose of this question (to make the idea more plausible) a vampire is not an undead creature. Rather:

  • A vampire is a human, infected by a symbiotic virus;
  • The virus is present in a vampire's saliva, spreading infection whenever it has contact with an uninfected human's blood (a bitten human becomes a vampire);
  • Perhaps a vampire's children are also vampires;
  • An infected human, perhaps after a period of illness, develops:
    • Increased ability to see in the dark, matching the best animals; However, also an increased eye vulnerability to intense light, to the point of having to squint eyes in lighting humans would consider "normal" and to the point of not being able to withstand the brightest hours of the noon;
    • Irises would become red (a side effect of the above eye mutation);
    • Maxillary canines would double their size (after some time of growth obviously); From this point on, all teeth, if broken or knocked out, would regrow slowly;
    • Skin would have a noticeably paler shade (understandable, since a vampire would be a primarily nocturnal creature, as opposed to an uninfected human);
    • A vampire would be able to digest blood; actually, a vampire would have to drink blood to survive (impaired body's ability to produce erythrocytes?)
    • A vampire's skin would become vulnerable to silver. Contact with silver would cause possibly severe burns. This would create problems in regions where silver was an established currency and/or material for minting coins.
    • They would also be allergic to garlic.
    • Maybe: A vampire would be able to survive by drinking animals' blood as well, not necessarily uninfected humans' blood, and wouldn't feed an uncontrollable urge to bite uninfected humans. Maybe this would depend on the variation of the virus?

Ah, and vampires would age and die from age normally. (To make this less troublesome).


  • How could such a virus evolve;
  • Why would this virus evolve to be actually beneficial for its host, rather than only causing severe diseases; are symbiotic viruses known in the nature at all?
  • A bitten human becomes a vampire; this implies an exponential rate of infection spreading (the more infected vampires there are, the more uninfected humans they can bite) - would there be any uninfected humans left after a few generations at all?
  • Partially for this reason I said about the lack of an overwhelming desire nor need to bite humans; wouldn't the virus, however, likely create such a need to hasten its spreading? (Might be explained by spreading through inheritance though, it might be "enough" for the virus)
    • Another possible explanation: The virus' variations which would necessitate drinking uninfected humans' blood or create an overwhelming urge to infect would die out either because, after a few generations, there would no longer be any uninfected humans alive whose blood could be drunk, or because humans would desperately fight and exterminate all infected individuals. Thus, less severe variations of the virus would be evolutionarily advantaged
  • Would the transformation be biologically feasible?
  • How could one explain the drawbacks, especially the vulnerability to silver and garlic? This seems arbitrary.
  • Why maxillary canines, wouldn't central incisor work better?
  • $\begingroup$ PS. I am aware of worldbuilding.stackexchange.com/questions/108805/… ; however; I still believe my question is different because I require vampires being infected humans, while the above question rules this out and requires vampires to be a separate race. $\endgroup$ – gaazkam Apr 10 '18 at 11:58
  • $\begingroup$ What exactly do you mean by the anatomy of a virus? Also how does one answer questions that basically ask "how does a virus evolve and for what reason"? Do you mean that there is some kind of cosmic plan, e.g. do you want metaphysical reasons? This stuff happens, to the best of my knowledge, randomly. Biology is basically a big random mess in which a few people recognize some patterns in. $\endgroup$ – Raditz_35 Apr 10 '18 at 12:07
  • $\begingroup$ @Raditz_35 (a) I wanted to type "anatomically correct vampires" however I was not allowed bc of the existence of the question I mentioned in the comments; so I typed "virus" to the title just to be able to post my quesion ;/ the tilte is bad, I know, but I'm not sure how to improve it ;/ (2) Is it possible for a virus to create such mutations? that's one thing; the other is, evolution is not a big random mess, but rather adheres to some laws, like natural selection. Bottom line, my question boils down to "is what I described possible at all", and I dont think such a question is senseless $\endgroup$ – gaazkam Apr 10 '18 at 12:20
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    $\begingroup$ Why do you absolutely want to make this into an anatomically correct series question? Why not simply ask "realistic vampire virus" or something? Mutations are random, if the new organisms survive depends on many factors. The natural selection part is irrelevant though because it already creates a strong symbiosis. What more information do you want? $\endgroup$ – Raditz_35 Apr 10 '18 at 12:28
  • $\begingroup$ @Raditz_35 (1)"Why not simply ask "realistic vampire virus"" Fine. (2) "The natural selection part is irrelevant though because it already creates a strong symbiosis." For this to be true the virus would have to have little to no effect on the host, which is not the case; also I described myself a few problems with this! (3) Again, is there such a thing like a symbiotic virus in nature at all?! (4) Can a virus biologically cause such mutations? (5) How to explain arbitrary vulnerabilites? (6) Other problems? Including the ones I may have missed? $\endgroup$ – gaazkam Apr 10 '18 at 12:41

The question has thought through the changes a virus would need to make to transform a human being into a vampire. In fact, this is the traditional model for a vampire. Such a virus is extremely improbable. The number & nature of changes suggest the virus would have to be a genetic engineering agent instead of a naturally evolved organism. This suggests intent.

Actually many of the changes needed to vampirize a human being are over-engineered and would exceed the reasonable limits of genetically engineered transformation. For example, growing fangs and gaining sufficient nutrition from blood. While other traits like paler skin would arise naturally if there was increased sunburn.

A number of the typical vampire traits might be beyond the reasonable limits of genetic engineering. However, if infected persons tended, for example, bite people and taste or drink any blood expressed by the wounds they inflict, then this make pass as a vampire-like characteristic. Without the need to go the full haematological diet.

A vampire virus if it is genetic engineering agent doesn't need to evolve and all its vulnerabilities would be built-in along with the other transformations. Why someone or something would create such an agent is puzzling. It wouldn't be the most effective biological weapon. Whatever intent was behind its development suggests a nasty streak of mischief. More a source of chaos and confusion than anything else.

While nature and evolution are capable of producing many remarkable and unexpected adaptations, a realistic vampire virus, more especially if it is going manifest the full repertoire of vampire characteristics, seems quite improbable. An artificially developed and manufactured viral agent that can modify human beings into entities that have a resemblance to vampires may be more likely. Although this capability is far beyond any technical feasibility of our current knowledge of genetic engineering.


From a more mundane perspective, the answer to at least some of these traits may lie in something we already have in our ecosystem; rabies.

It's entirely possible that the disease is actually the source of at least some of the vampire trait descriptions in that it generates significant behavioural changes, makes people avoid things like sunlight and water, and is spread by bats (among other animals of course).

There is some interesting research coming out that shows that it might be possible to survive rabies by being placed in an induced coma at the beginning of symptoms appearing. In humans, by the time that happens it's too late for vaccines and immunoglobulins to work because most of the internal and neural damage has already been done. We also know that the virus can remain dormant in an otherwise uninfected host for some time.

So, start there. Have rabies mutate into something that puts you into a coma, effectively suspending the neurological damage in the body until such time as the immune response kicks in, but the immune response merely deactivates the virus in the body, doesn't incapacitate it.

The teeth and the blood drinking are difficult to deal with because as has already been pointed out this would be a mutation and those by definition are inherently random in all hosts. But, say the virus acts as a very specific mutagen on a particular part of Human DNA that triggers a known change like this most of the time. Some of your newly infected would die, but those who survived would carry the new found traits.

Silver is actually easy in that it's a known disinfectant, so it's possible that the silver in close proximity would cause discomfort because of the increased levels of contagion in the body. The blood works better with rabies if it can be 'injected' directly into the bloodstream of your new vampire, as one of the side effects of rabies is constriction of the throat. This could mean that they actually need their blood 'replaced' from time to time with nutrient and energy rich blood to survive given that ingestion of anything is close to impossible. But, your previous mutations could make this a reality by giving the canines an artery that can be fed directly from whatever the vampire bites.

If your rabies virus mutation actually slowed down the metabolism, this would mean that your vampire could actually survive through regular blood 'transfusions' in this manner, and would likely have an extended lifespan. This would in turn lead to an increased aversion to the sun as such a metabolic change would likely be due to lowering the core temperature meaning that your vampires would greatly prefer the cold and would likely overheat during a normal day's temperature, making them 'burn up' in the sun. Not literally of course, but certainly they would overheat to the point of exhaustion, especially with constricted throats that prevent the intake of water.

They would however lose any chance at rapid healing, super speed or strength, and any other feature of an increased metabolic rate.

All in all, this would have to be the closest real life possibility for such a virus although given that rabies is currently deadly (save possibly for induced coma treatment) the chances of this kind of mutation occurring naturally are incredibly slight.


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