Monsters from the ancient and medieval eras were primarily large pedators. Think the Nemean Lion or the Calydonian Boar, both extra-large, extra-powerful versions of frightening wild beasts. Or the Minotaur, half man, half beast. Or the fire-breathing dragon of the Middle Ages.
But as we enter the Renaissance, stories about large predators begin to take a back seat to stories about human-like monsters infected with a deadly contagion. Think the vampire, the werewolf, the zombie. As the wild areas of Europe began to be conquered and predators driven extinct, human populations grew more dense and there was a lot more danger from contagious disease than from lions or boars.
The author makes an interesting case that stories of vampirism or lycanthropy may have originated from the disease rabies. Today, rabies is controlled, but in the 1700’s, there was a rabies epidemic among wolves and dogs. The rabies virus, in humans, causes patients to wander restlessly. They drool bloody saliva, retract their lips, and cough and gasp. They can be highly aggressive, and the disease is spread by being bitten. The animals most likely to spread rabies to people are, notably, the dog, the wolf, and the bat.
Tuberculosis was also epidemic during the same time period and may have influenced myths as well. It had a long incubation period and caused people to waste away.
Nowadays, vampires and werewolves are more likely to appear as the protagonists in romance novels than the villains in horror stories. This may suggest that contagion-based monsters have largely run their course. Rabies and tuberculosis are well controlled in the western world, and the concept of contagion is well understood. So now we have sparkly vampires.