Corrupted Blood Incident

The Corrupted Blood incident is a video game glitch and virtual plague that occurred on September 13, 2005 in the MMORPG World of Warcraft. The epidemic began with the introduction of the new dungeon Zul'Gurub and its end boss Hakkar who, when confronted and attacked, would cast on players a hit point draining and highly-contagious debuff spell called "Corrupted Blood."

The spell, intended to last only seconds and function only within the new area of Zul'Gurub, soon spread across the virtual world when players discovered that the use of teleportation spells could take the affliction out of its intended confines. By both accidental and purposeful intent, a pandemic ensued that quickly killed lower-level characters and annoyed higher-leveled ones, drastically changing normal gameplay, as players did what they could to avoid infection. Despite measures such as programmer-imposed quarantines, and the players' abandoning of densely populated cities (or even just not playing the game), the epidemic was only finally controlled with a combination of patches and resets of the virtual world.

The conditions and reactions of the event attracted the attention of epidemiologists for its implications of how human populations could react to a real-world epidemic. Anti-terrorism officials also took notice of the event noting the implications of some players planning and perpetrating a virtual biological attack.