In one of the books of the The Witcher series Geralt has been told by a vampire (Regis, if I recall) that it was not true that vampirism could be spread by bite. He elaborated that the whole idea was ridiculous. If I recall, the argument was something like this: if that was the case, vampirism would spread exponentially, quickly infecting everyone. Since the majority of people are not vampires this shows that vampirism cannot spread by bite.
Is this true that, realistically speaking, if vampirism could be spread by bite then everyone would quickly be doomed to become vampires? Or does, contrary to this argumentation, the traditional setting where only the minority of people are infected with vampirism and vampires are largely kept at bay make sense after all?
Let's look at real world viral diseases. Rabies would, perhaps, be most similar to vampirism. To quote Wikipedia:
The virus is usually present in the nerves and saliva of a symptomatic rabid animal. The route of infection is usually, but not always, by a bite. In many cases, the infected animal is exceptionally aggressive, may attack without provocation, and exhibits otherwise uncharacteristic behavior. This is an example of a viral pathogen modifying the behavior of its host to facilitate its transmission to other hosts.
However, the window of time when the virus can infect others is relatively short:
The symptoms eventually progress to delirium, and coma. Death usually occurs 2 to 10 days after first symptoms. Survival is almost unknown once symptoms have presented, even with intensive care.
Even its name describes what it does to its victims:
The name rabies is derived from the Latin rabies, "madness". This, in turn, may be related to the Sanskrit rabhas, "to rage". The Greeks derived the word lyssa, from lud or "violent"; this root is used in the genus name of the rabies virus, Lyssavirus.
So why did rabies not infect all animals (and humans) yet? I'm not an expert, but I'd hypothesise that it is too harmful for its own good. It kills too quickly and while it makes animals aggressive to increase the likelihood of it spreading through bites it also makes symptomatic animals nigh insane and alters their looks to pretty much broadcast the message that something is seriously wrong with them and everyone should run away as quickly as they can. To quote an anecdotal report from Quora of a man meeting a rabid dog:
The dog noticed me and started running in my direction. There was something wrong - its head was cocked to one side and its jaws were slavering, the white drool around its mouth coating its matted fur.
What if there was a virus somewhat similar to rabies, but less malignant? Wouldn't it remove the obstacles of its uncontrollable spread?
To be more precise, the virus would:
- Not kill symptomatic people quickly, carriers wouldn't die much sooner than non-infected individuals;
- Not inconvenience carriers much; alternatively, it could balance off the inconveniences (eg vulnerability to sunburn) with perks (eg night vision) - what I mean here is that carriers shouldn't have a much higher chance to die because the inconveniences make them more vulnerable to other threats; in particular, it should not make carriers insane, or at least, not the majority of time;
- Like rabies, however, force carriers to display aggression towards non-carriers and a strong desire to spread the virus by biting others.
If such a virus could infect humans, would all humans soon become infected?
Perhaps mankind would spread into two camps, those not wanting to get infected and those embracing infection, two camps at a constant war with each other... But given that people could only move from the "not infected" to the "infected" camp and not the other way around, wouldn't the "infected" camp not be destined to eventually win? Also, wouldn't most people just want to get bitten ASAP if for no other reason then for the sake of peace?
To make things simpler let's assume that such "vampires" would not have to feed on blood. If they did have to drink blood then I guess the worst case scenario would be a dystopia where non-infected people would only exist to donate blood to infected people...
I would really like to somehow salvage the traditional setting, but given the above I'm not sure if this is possible... Do non-vampires have any chance?