The Great Space Plague was a disease that spread to multiple planets. In the aftermath, the Inter Minorians stopped trading with other planets as a precaution against contamination. (TV: Carnival of Monsters)
The Draconians were among the species afflicted by the Space Plague, (PROSE: Catastrophea) during the reign of the fifteenth emperor during the 21st century. (TV: Frontier in Space) The Second Doctor cured the plague on Draconia and was rewarded with the rank of noble. (PROSE: The Dark Path)