Players who logged into World of Warcraft on September 13, 2005, were introduced to patch 1.7, which included the new 20-man raid Zul’Gurub.
In the remote jungle of Stranglethorn Vale, this raid introduced a powerful new boss: Hakkar the Soulflayer. Hakkar had a unique ability called Corrupted Blood, which would infect players with a damage-over-time debuff that also spread to nearby allies.
It was meant to serve as a short-term challenge during the fight, not something that would leave the raid itself. But then, things unfolded in a way that completely contradicted that assumption. The Corrupted Blood debuff caused an initial hit of minor damage, then continued to tick every second for 10 seconds.
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+ 2If another player or pet was close by, they might catch the infection as well. It made the raid mechanic both hectic and entertaining. The problem, however, lay in how it interacted with Hunter pets. If a pet gets infected and is dismissed mid-fight, the debuff stays frozen.
When the pet was summoned later—say, in a city full of players—the infection came right back to life, and so did the spread. Blizzard didn’t foresee this loophole, which caused a raid-exclusive mechanic to spill over into the open world.
It was too late by the time players understood what was happening. It wasn’t long before Corrupted Blood became a digital pandemic of epic proportions. Some accounts go as far as to call the Arimoon server the first to collapse, with Ironforge and Orgrimmar becoming the epicenter.
In the ensuing days, millions of players found themselves affected. Blizzard’s tools couldn’t keep up with the speed of the disease. Server-wide panic broke out, and in that chaos, a very human story began to unfold. The cities of Azeroth quickly became graveyards, with corpses littering the streets.
Fresh players didn’t stand a chance, and even seasoned veterans had to tread carefully to make it out alive. Players turned to chat channels for real-time alerts, and some decided to log off until the situation settled.
Others took on the role of first responders, using healing magic and warning everyone of the outbreak’s reach. A handful of players made it their purpose to spread the infection. They used pets, mounts, and even NPCs to reintroduce Corrupted Blood into areas that had just been cleared. Some stood at city gates just to infect newcomers.
Others lied about having cures and sold useless items to desperate players. The social dynamics shifted dramatically—cooperation, sabotage, greed, altruism—it was all there. Blizzard initially implemented quarantines, locking down certain areas, but the infection always escaped.
Then came the server resets, but with each raid run and step repetition, the whole process started from scratch. Eventually, Blizzard deployed a hard patch that prevented pets from carrying Corrupted Blood outside the raid.
The servers were rolled back to a pre-infection state, and the event officially ended on October 8, 2005. The Corrupted Blood incident is still remembered not just as an oddity but as a turning point in how digital worlds are viewed. Players acted the same way people do in real-world pandemics.
Some stuck to the rules, some threw them out the window, and some made things worse on purpose. The incident eventually became a reference point for understanding how people behave during pandemics. The event was analyzed by researchers, including Dr. Nina Fefferman and Dr. Eric Lofgren, who compared it to real-world disease outbreaks in their academic papers.
The CDC even contacted Blizzard, although no data was gathered during the outbreak itself. Players showed patterns of behavior almost identical to those seen in real-world epidemics: self-isolation, panic, misinformation, refusal to comply with containment, and even deliberate sabotage.
It was clear that even in a fictional world with no real consequences, human reactions to perceived threats were often familiar and irrational. The idea was dismissed by some scholars early on, who argued that people wouldn’t behave the same in real life.
click to enlarge + 2But when COVID-19 came around, those in-game actions like dodging quarantine, doubting the facts, and infecting others started to match the real world in a pretty uncomfortable way. WoW’s 2025 Season of Discovery brought Corrupted Blood back, using infected pets and NPCs once more.
Social media exploded with footage of the “reborn plague,” and Blizzard eventually patched it out. But the moment proved that even two decades later, the fascination with this virtual disaster hasn’t faded.
Whether studied by scientists or remembered by players, it’s an unforgettable part of gaming history. And even today, it still says more about us than most stories ever could.
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