The infection originated from Hakkar the Soulflayer -- the boss of classic gold wow this very initial 20-player raid Blizzard released. Hakkar would toss Corrupted Blood on gamers and it would damage them for about 10 minutes. Players would disperse the effect to others if they got too close to those infected. After the 10 seconds were completed, or players finished the boss battle, the damaging effect was supposed to finish. Only it did not.

A programming oversight allowed the debuff to spread beyond the site of the Hakkar boss struggle and into the world at large. Hunter characters may summon and dismiss pets to fight in their side at will. Once ignored, all of the consequences on the pets are paused until it is known as back out again. In consequence, the critters could contract Corrupted Blood through the boss fight, vanish then display the symptoms again elsewhere in the world map when they were summoned. There it would spread to other players and pets which came in contact with them.

Cities like the dwarven city Ironforge and orc town Orgrimmar were overrun in hours. Non-playable personalities, who could not die as a result of particular coding, could also catch the effect, meaning any player who passed by them could receive Corrupted Blood.

Once word got out, players searched frantically for buy wow gold classic news about what was going on.