Online game worlds may be a useful tool for studying the spread of human infectious diseases, according to scientists from Rutgers University (Piscataway, NJ, USA) and Tufts University (Boston, MA, USA). Writing in the September issue of The Lancet Infectious Diseases, Eric Lofgren and Nina Fefferman describe how a programming error in a popular online role-playing game, World of Warcraft, caused a full-blown epidemic of a virulent, highly contagious disease. Although computer models of infectious diseases are of increasing importance, a limitation of these models is that they cannot predict the behaviour of individuals. Lofgren and Fefferman realised that appropriate exploitation of online games may alleviate this constraint since players' economic and social behaviour often mimics their real-world behaviour.
The outbreak began when Blizzard Entertainment released an update in September 2005, allowing higher level players to access a new area of the game. Players experienced combat with a powerful creature called "Hakkar", who occasionally infected players with "Corrupted Blood." To the powerful players Corrupted Blood was no more of a hindrance than a cold, but a game-wide epidemic started after many characters teleported—a common feature of the game—back to urban areas before being killed or cured of the disease, where they infected more susceptible players.
Blizzard Entertainment's quarantine strategy failed because of the highly contagious nature of the disease, the inability to seal off a section of the game world effectively, and player resistance to the notion. Fortunately, the game developers had one additional option not available to public-health officials: resetting the computers.
This is the first time a virtual virus has infected a virtual human being in a manner even remotely resembling an actual epidemiological event. Currently, epidemiologists face major constraints in studies of diseases dynamics because they are limited to observational and retrospective studies. Computer models allow for experimentation on virtual populations without such limitations, but they rely on mathematical rules to approximate human behaviour. By contrast, human-agent virtual simulation may bridge the gap between real-world epidemiological studies and large-scale computer studies by including the variability and unexpected outcomes that arise as a result of the behaviour of individuals.
Lofgren and Fefferman say: "We believe that, if the epidemic is designed and presented so as to seamlessly integrate with the rest of the persistent game world, in such a way as to be part of the user's expected experience in the game, a reasonable analogue to real-world human reactions to disease might be observed and captured within a computer model. . . By using these games as an untapped experimental framework, we may be able to gain deeper insight into the incredible complexity of infectious disease epidemiology in social groups."
Journal
The Lancet