Warcraft: When A Virtual Plague Tore Through Azeroth

Usually, World of Warcraft is only described as an epidemic by obnoxious fitness enthusiasts or the curmudgeonly, but that descriptor once took on a much more frightening, literal meaning.

Though it sounds like a joke or a hoax at face value, there was once a time that a virtual disease spread throughout the World of Warcraft, culminating in an epidemic that had a far-reaching impact beyond the realm of video games.

The story begins on September 13, 2005, when Blizzard introduced a new raid in WoW called Zul’Gurub. The ancient Troll city, nestled in the dense jungles of Stranglethorn, was home to a grim rogue’s gallery of Witch Doctor’s and tribal chieftans. One in particular cast a debilitating debuff on players called Corrupted Blood. The debuff worked like a plague, quickly damaging players’ own vitality and even spreading to others in the group like a real-life, contagious disease. The plague was meant to be confined to the raid and to only last a few seconds.

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Of course, that last sentence is the starting point of all the great zombie and virus sci-fi, isn’t it? For while the Corrupted Blood disease was supposed to stay in Zul’Gurub and dissipate from players relatively quickly, Blizzard neglected to make the disease totally vanish from players’ pets. If a player’s pet caught the disease during the fighting and was then dismissed, it would still retain the illness even if summoned outside of the raid’s confines. This little oversight allowed Corrupted Blood to spread outside of Zul’Gurub, and Azeroth quickly went to hell from there.

Players carried Corrupted Blood with them back to World of Warcraft’s in-game cities, where the disease spread among both players and NPCs like wildfire. Though NPCs couldn’t die from the illness, they functioned as asymptomatic carriers and managed to spread it to other players. The disease killed low-level players in seconds, and even vets could only stay alive by chugging health potions and avoiding crowds of other characters. To this day, there are inveterate Warcraft players who recall seeing hundreds of bodies lining the streets of Azeroth’s major cities.

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Over the course of the next week, players continued to respond and act as victims of real-life pandemics do. Major population centers like Stormwind and Ogrimmar were avoided, and some cities were depopulated altogether. Players intent on eluding the illness struck it out alone in the wilderness, hiding from anyone that might bring Corrupted Blood to their character. Blizzard imposed quarantines on disease-heavy portions of the world to little avail.

Players responded in ways other than simply fleeing, though. Those who had created healer characters volunteered their services to the afflicted, while other players directed healthy characters to disease-free areas. Just as looters take advantage of natural disasters, there were opportunistic players who cheated and stole while everyone was preoccupied with Corrupted Blood. Because Internet trolls are a fact of MMO life, some players even spread the disease for their own amusement.

Finally, after a week, the carnage ended. Blizzard managed to patch the Corrupted Blood bug and the world slowly returned to normal. Players returned to cities, raids continued as usual, and pets no longer secretly carried the Corrupted Blood illness out of Zul’Gurub. Just like Europe in the aftermath of the Black Death, the realms of the Horde and the Alliance could finally rebuild.

To this day, the Corrupted Blood incident remains one of the most fascinating events in MMO history. The semblance between the Corrupted Blood incident and real-world plagues was eerily similar, as players took precautions not unlike those undertaken by healthy people in disease-stricken areas of the world. Epidemiologists from prestigious medical universities examined the incident and proposed that computer games could, in many ways, be used to model real-life epidemics. The Corrupted Blood incident may have helped spur funding into such research.

The Corrupted Blood plague remains unprecedented in the saga of MMOs. No event before or since has had such accidentally far-reaching effects in a digital world, and effects so creepily akin to epidemics in history and in science fiction. The incident helped bring video games to the forefront of medical technology, and serves as yet another example of how human behavior in the real world may not be all that different from behavior in a massively multiplayer title.