Virtual epidemic in World of Warcraft The Corrupted Blood incident took place between September 13 and October 8, 2005, in World of Warcraft, a massively multiplayer online role-playing game (MMORPG) developed by Blizzard Entertainment. When participating in a certain boss battle at the end of a raid, player characters would become infected with a debuff that was transmitted between characters in close proximity. While developers intended to keep the effects of the debuff within this boss's game region, a programming oversight soon led to the debuff becoming an in-game pandemic that spread throughout the fictional world of Azeroth. 1,445,989 views on September 13, 2016 — Wikipedia's most-read article that day. Also most read: Yma Sumac, HTTP 404, Unfinished portrait of Franklin D. Roosevelt, V-J Day in Times Square. Wiki link