I don't know how much of this story is a legend or not but this is how a scientific (Claude Lorius) for the idea of collecting data from the air bubbles trapped in the arctic ice. (This data is now the base of climate science)
After a day of drilling on the arctic, as they were releasing in the evening they decided to use ice cubes from the ice they just drilled for their whisky. Drinking ice that is several hundred thousands years old is quite cool. While drinking the whisky the scientific noticed the air bubbles coming at the surface, then he got the idea that of he could analyze the air trapped in the ice he would get information about the atmosphere of the past.
Medical: vampires are just people affected by rabies.
People with rabies become adverse to strong odors (like garlic) or stimuli, like watching himself in the mirror. Biting of course is part of the symptoms and the disease is transmitted through bites.
After death it's common for these people to have blood oozing from their mouth, as if they bite someone just before.
And guess what nocturnal animal is carrying rabies ? Vampire bats.