World of Warcraft News & Events & Guides
Although limited to only a few of the game's servers the numbers of characters that have fallen victim is thought to be in the thousands.
Originally it was thought that the deadly digital disease was the result of a programming bug in a location only recently added to the Warcraft game.
However, it now appears that players kicked off the plague and then kept it spreading after the first outbreak.
Since its launch in November 2004, World of Warcraft (Wow) has become the most widely played massively multiplayer online (MMO) game in the world.
Its creator, Blizzard, claims that now more than four million people are regular players.
Wow is an online game that gives players the chance to adventure in the fantasy world of Azeroth that is populated by the usual mixture of humans, elves, orcs and other fantastic beasts.
As players explore the world, the characters they control become more powerful as they complete quests, kill monsters and find magical items and artefacts that boost abilities.
The Warcraft world is a familiar fantasy setting
To give these powerful characters more of a challenge, Blizzard regularly introduces new places to explore in the online world.
In the last week, it added the Zul'Gurub dungeon which gave players a chance to confront and kill the fearsome Hakkar - the god of Blood.
In his death throes Hakkar hits foes with a "corrupted blood" infection that can instantly kill weaker characters.
The infection was only supposed to affect those in the immediate vicinity of Hakkar's corpse but some players found a way to transfer it to other areas of the game by infecting an in-game virtual pet with it.
This pet was then unleashed in the orc capital city of Ogrimmar and proved hugely effective as the Corrupted Blood plague spread from player to player.
Although computer controlled characters did not contract the plague, they are said to have acted as "carriers" and infected player-controlled characters they encountered.
The first server, or "realm" as Blizzard calls them, (Wow Gold)affected by the plague was Archimonde; but it is known to have spread to at least two others.