Travel was also an important element; though international airports are absent from the medieval setting of World of Warcraft, infected characters often "teleported" from battle areas into crowded town squares, often infecting the dozens of characters unfortunate enough to be near their points of entry.
When game developer Blizzard Entertainment Inc. of Irvine, Calif., grasped the devastating nature of the disease, it set up voluntary quarantines, which, predictably enough, were summarily violated by many, allowing the illness to spread further within the virtual realm.
"Probably the single most interesting thing for me was the player resistance to the notion of quarantine," Schaffner said, adding that the event could hold further interest for pandemic researchers due to the nature of the infection.
"This is a highly contagious infection they created," he said. "That's reminiscent of influenza."
The resulting pandemic spread, contained only by the separate servers on the game's mainframe. And though Lofgren said the event was so unexpected that an accurate account of all of the deaths could not be made, the character death toll over a few short days likely reached into the thousands.
"A lot of capital cities on servers that were infected had to be abandoned for a while," he recalled. "There were major disruptions of commerce."
"You had whole cities that essentially became uninhabitable."
Fortunately for World of Warcraft's varied populace of warriors, orcs and mages, the Corrupted Blood pandemic was short-lived — ultimately solved by a few timely lines of code and a click of the reset button to instantly resurrect all who had perished.
"We were able to fix it within a week of discovery," said a Blizzard spokesperson. "During this time, we worked closely with our community to inform them about the bug and let them know that a fix was in the works."
But Fefferman said the online realm's tragedy could be the real world's gain if such a tool could be harnessed for infectious disease research.
"That's my hope — that it will become a new framework for scientific experimentation," she said. "Without actually putting anyone in danger, we can see these behaviors occur."
Lofgren agreed. "It's a compelling idea. … A computer simulation relies on a series of assumptions. Most researchers recognize, however, that people aren't governed by a rigid set of rules."
If such a "planned pandemic" occurs, however, don't expect to see it on World of Warcraft. A Blizzard spokesperson said that there are no current plans to replicate the experience.
"Since World of Warcraft is first and foremost a game, our design decisions are determined by what will provide the most entertaining and enjoyable experiences for our players," the spokesperson said.