The Saurian virus was a viral disease.
While on Dramia II in 2251, Dr. McCoy treated a Dramen colonist named Kol-Tai, who was afflicted with a strain of the Saurian virus. Antibodies created to combat the Saurian virus were later discovered by McCoy to be the cure for the Dramia II plague that afflicted the crew of the USS Enterprise. (TAS: "Albatross")