In 2005, World of Warcraft introduced a new raid: Zul’Gurub, with its final boss, Hakkar the Soulflayer. And with Hakkar came a special ability called Corrupted Blood.
This was an (initially) time-sensitive hit-point draining spell that could be continuously spread to another player, if close enough — like a virus. Eventually, they’d die. Players soon discovered a glitch that could take the Area of Effect (AoE)-based infection out of the raid using their pets and minions, quickly leading to an unprecedented virtual pandemic in 2005. Within hours, entire in-game cities like Ironforge and Stormwind City were infected, including NPCs who could spread the virus without dying.
