A User-Friendly Computer Virus

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image by Richard Borge

Skeletons paved the cobblestone streets. Thousands succumbed to the blood plague quickly, but others lingered, only to infect everyone they met. No one was safe. Warriors, mages, and healers all fell. Word spread, urging everyone to flee, but still the plague raged on.

Within days, World of Warcraft, a hugely popular online adventure game, was devastated.

Although death in World of Warcraft is a mere annoyance–the character disappears for a minute or two and then rematerializes–the plague proved unstoppable. Eric Lofgren was playing the game during the virtual outbreak in September 2005. “Early on, it wasn’t clear how it spread or what was going on,” says Lofgren, who at the time was an epidemiology student at Tufts University in Boston. Some players tried to heal others, not realizing they would spread the plague. “There was a lot of confusion.”

It took Blizzard Entertainment, the Irvine, California, company behind the game, nearly a week to stop the virtual plague. At that time the online Tolkienesque world of swords and sorcery boasted 4 million subscribers (it now has more than 9 million). The company’s programmers had created Hakkar the Soulflayer–a monster so strong that players would have to band together to kill it–to enrich the game. They expected his blood curse to remain localized. But they hadn’t accounted for human behavior.

Afflicted players teleported to towns. Soon, their virtual pets became infected. Both humans and beasts spread the disease to densely populated areas. Game-controlled characters such as shopkeepers became infected but didn’t die, acting as silent carriers–virtual Typhoid Marys.

When Lofgren told his then-adviser, Nina Fefferman, about the virtual chaos, she called Blizzard. Enticed by parallels between the virtual and actual outbreaks, Fefferman, a specialist in computer modeling of infectious diseases, asked the company to preserve the plague data. “They said, ‘This is a bug, we’re worried about fixing it, we’re not worried about logging data for you.’ “

Minus Blizzard’s help, Fefferman and Lofgren still learned enough from observing the outbreak, reading accounts on game-related websites, and interviewing players to publish a paper in the Lancet Infectious Diseases in September 2007 outlining the potential lessons of virtual outbreaks.

Computer programs that model how infectious diseases spread aren’t new. Government and university researchers have been developing them for decades. But, say Fefferman and her colleagues, studying the actions of the millions of people invested in online worlds could substantially boost the reality quotient of disease simulators.

“The [computer] models we have are incredibly good at figuring out what the disease will do once we know what the behavior of the person is,” Fefferman says. But the models make broad assumptions about how people will behave, and “we’re pretty bad at knowing what those assumptions should be.”

In March 2007, Ran Balicer, an epidemiologist at the Ben-Gurion University of the Negev in Beersheba, Israel, published a paper in Epidemiology outlining two particularly striking parallels between Hakkar’s curse and real epidemics. First, virtual teleporting is like air travel, spreading bugs such as severe acute respiratory syndrome, or SARS, across the world in a flash. Second, animals often act as reservoirs of human disease, as is the case with avian influenza.

More interesting to Fefferman is the “complete diversity” of player behavior that was reported. Some players logged out–a panic response with obvious parallels in the real world. Others, called “griefers” because they rejoice in virtual destruction, deliberately spread the corrupted blood. Still others put themselves at risk to heal the infected, not unlike first responders to, say, the Ebola outbreak in Africa.

One of the more interesting group dynamics, says Fefferman, was the influx of characters to disease epicenters. Many came just to be near the action. In a game where the cost of virtual death is small, this type of thrill seeking makes sense. But Fefferman and others say it’s conceivable that similar behavior would emerge during a real epidemic.

“It goes well beyond curiosity seeking,” says William Sims Bainbridge, a program director of the National Science Foundation’s Human-Centered Computing Cluster. “If you believe, as I do, that the federal government can’t succeed in containing” a smallpox outbreak, Bainbridge says, “you would rush to the place where they were giving immunizations, knowing that the smallpox was going to get everyplace pretty soon.”

After gleaning early lessons from the accidental World of Warcraft outbreak, Fefferman now wants to insert a planned epidemic into a game world. To date, though, large game companies have taken a pass on partnership.

In the face of reticence from the industry, some academics are instead designing their own worlds, though they face significant obstacles. Online games cost millions of dollars, require the talents of dozens of programmers and artists, and devour huge advertising budgets to attract their minions.

Despite the hurdles, the programmers of Whyville have managed some success. Launched in 1999 as an education and research tool, the free world for 8- to 15-year-olds now boasts some 3 million users, according to Numedeon Inc. of Pasadena, California.

Several times programmers have introduced outbreaks of Whypox, which stippled the faces of the users’ avatars with red bumps and interrupted their text chats with “Achoo.” Yasmin Kafai, a University of California, Los Angeles, education professor who studies Whyville and its users, says that offline, kids vigorously debated the cause of the outbreak and how it spread. “It turned out to be a really good learning tool for the kids,” she says.

Epidemiologists hope that online worlds turn out to be good learning tools for them, too.

Excerpted from Science News (Oct. 27, 2007). Copyright © 2007 Science Service. Subscriptions: $54.50 (52 issues) from 1719 N St. NW, Washington, DC 20036; www.sciencenews.org.

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