Drywell Fever
Drywell Fever was the Common name for an illness which swept through the Nentir Vale in the 9th century of the Middle Era. It was a bio-magical experiment created by the sadistic dragon Nix the Black; it resulted in thousands of deaths.
A mutated strain of Drywell Fever, Iceblood Plague, was known to be an adaptation of the sickness caused by magical interactions with the Elemental Plane of Water.