Inspired by Gustavo Souto's Vampires Exist session (silviolobo.com.br/gustavo), I decided to seek an important source on the internet. The original is in English; here is a Brazilian version.
A seemingly innocent question that once confused a group of people, resulting in much controversy and dispute, but now in contemporary times, this question is considered by the vast majority to be ridiculous and nonsensical, no more than mere ineffable trash, with evidence being nonexistent. However, this was never the case.
Evidence supporting the existence of vampires has always existed in our society since the spawning of these creatures. They were simply well hidden from the public, having many things... (aliens/UFOs and werewolves)
A piece of obvious evidence would be the fact that there are descriptions of vampires from a matrix of pre-existing data and cultures worldwide. Drawings and written descriptions of humans as creatures that drain blood from their victims, with mysterious strength, speed, elongated teeth, varying skin pigmentation, aversion to sunlight, and allergy to garlic. The underlying, rudimentary characteristics, as described above, all correlate and maintain coherence across different cultures. There are descriptions of vampires extending worldwide from places like Africa to India to China.
The existence of vampires in various cultures is an obvious indication that there is something similar, if not identical, to the described creatures in our world.
Eyewitness accounts are few and limited to hundreds, and rarely thousands, globally each year, with described encounters also having a strong correlation with each other. Globally, the evidence for the existence of vampires is scarce but effectively strong. Eyewitness accounts still exist within the hundreds, and even if a strong percentage of these encounters are the result of fraud, conjecture of the mind, etc., the remainder accumulated over time is still important in itself. The existence of vampires in cultures also suggests that they were (if not are) abundant and prosperous.
In conclusion, if we are to accept the existence of vampires, then there is a set of explanations suggesting why they are rarely seen. However, before we can recognize these, we first need to accept the different species or types of vampires and their characteristics:
(The following set of explanations have been intentionally adapted to be brief, succinct, and concise and were derived from authentic sources.)
1. True Vampires: These were the vampires that were first supposedly generated from the ruins of hell by Lucifer himself, sent to inflict evil and suffering on Earth. They were once strong, but God punished them and made them suffer, making them sensitive to light and garlic, as well as diminishing their strength and longevity. These vampires are the true ones, whose blood has not been contaminated with the human gene and are pure. There are few of them left in our modern society, and most of them are in stasis (long periods of hibernation extending from years to centuries). They have different skin pigmentation from us, non-retractable, elongated teeth, an aversion to the sun, and are sensitive to garlic. They may also have pointed ears and slanted eyes.
2. Modern Vampires: These vampires are a hybrid amalgam of vampires and humans, with different characteristics as a consequence of different gene relationships. In most modern vampires, the vampire gene is weak, having been contaminated by human genes, and compared to a true vampire, they are almost nothing. The most common characteristics include: retractable elongated teeth, slight aversion to light, and possibly an aversion to garlic. They are almost indistinguishable from humans. There are different species of the common modern vampire.
3. Psychic Vampires: These vampires feed on energy rather than blood and are biologically speaking Homo sapiens.
4. Sanguinarians: Humans who simply drink blood...
Vampires reproduce in the same environment as us, offspring and fulvous with shared DNA through the union of male and female parts. However, they have also been able to produce offspring through biting, yet these offspring do not share common DNA with the vampire that bit them. The deciphering of the vampiric virus was a technique that was abandoned as the number of true vampires decreased. The virus still exists in true vampires (but they are undergoing stasis) and would have undergone mutations, making it weaker, although remaining in the host. (The strength of true vampires has dramatically decreased)
The stereotypical notions surrounding vampires were authentic but cannot be adequately applied to today's vampires (mainly modern ones). For example, a wooden stake through the heart was a biblical technique introduced by a priest who received a message from God when his monastery was attacked at night and his brothers were murdered by vampires, that the wooden stake would take their souls to hell.
There are several sub-species of modern vampires, Wampyrus (Homo), for instance, Homo Wampyrus Draco.
In any case, now that general information about vampires has been covered, a list of reasons why these vampires are not frequently seen in public will follow:
1. True vampires are not seen because they are all in long-lasting stasis and are hidden in dark places where sunlight cannot penetrate or is at an effective minimum.
2. Modern vampires are practically physically indistinguishable from humans.
3. Vampire attacks are rare because most vampires obtain blood through friends or donors. Government agencies supposedly support them, also providing sustenance.
4. Most vampire sightings are by trained professional vampire hunters (usually working separately from governments, thus maintaining effective secrecy). They are also experts at easily distinguishing vampires from humans.
5. Most vampires DON'T even know they are vampires! (The aversion to the sun is natural and coincides with many illnesses, and the desire for blood can be seen as a mental disorder, while agility and grace, and any other athletic characteristics can be considered natural. Modern vampires may not even possess athletic qualities, depending on the strength of the vampiric gene residing in them.)
In general, vampires exist and always have existed. Historical records of vampires are present, and sightings/encounters exist, but biological variations may not necessarily be detected due to our current technology being inferior to what is required. The global view of vampires as strange, eccentric creatures is fallacious. They can simply be seen as people with different needs and functions than us. (The terms "true vampires" and "modern vampires" are often used interchangeably due to the lack of true vampires present.)
Here are some websites about vampires: www.haemavore.com



