The Lillith Virus, named for Adam's first wife, was first found in an ice core sample from Antarctica. It's spread through the human population was rapid.
A primitive sibling of EDS, Electromagnetic Sensitivity is a rare affliction that grew to prevalence in the late Petroleum Era, and persists into the Cosmic Era. What was formerly a psychosomatic form of hypochondria is a recognized, and paradoxically, officially discredited disease.
Elephants crossing the seas!
It is not an infectious disease, but it is a plague upon the world.
For it spawns villains. And not your garden variety villains, but epic villains, master villains of the most dangerous kind Evil Geniuses.
Pnathic sorcery has existed for ages, crudely used by magi who no idea the true forces they were fumbling with.
An article concerning the nature and role of druids in an RPG enviroment.
Of creatures great and small
The Omen Plague has other names. It is known as The Star Plague and even The Mundane Plague. It is still with us today, now known by the common name of the Shaking Death. To set the stage, the stars were aligned in all the wrong signs. Everyone new something bad was going to happen. When winter set in hard and early, they thought that was it. They were wrong.
Plagues and other great diseases are important parts of history and some settings. They defy man and may even defy God in their swift and terrible punishment upon the body of society.
Surnames: The Chinese were among the very first cultures to adopt the use of hereditary surnames (around 2800 BC). But the custom didn't quite catch on in Europe - at least not until the Venetian aristocracy made it popular sometime between the 10th and 11th centuries AD. What culture made it popular in your setting and why?