A space plague was a type of disease.
During the mid-21st century, the Second Doctor (PROSE: The Dark Path) helped the Draconians deal with an outbreak of space plague. He was ennobled for his efforts. (TV: Frontier in Space) This outbreak was specifically identified as part of the Great Space Plague. (PROSE: Catastrophea)
A space station threatened by a space plague was saved by disinfectodroids. However, their obsessive programming made them clean up everything, including the station occupants, and dumped them all on an alien planet. The Tenth Doctor and Rose Tyler were sent to the same planet when they arrived on the station. (COMIC: The Germ War)
Alternate timeline Edit
In one alternate timeline in which the UK-201 never crashed on Dido and made it to the planet Astra, Vicki Pallister's daughter, Carla Dalton, left to aid the Outer Provinces during an outbreak of space plague. She died in a rebel attack. Some years later, Jeran Dalton, Vicki's husband, attended a conference seeking to deal with the spread of the plague. While there, he succumbed to the disease himself. Vicki later altered the timeline further, saving both their lives. (AUDIO: The Crash of the UK-201)