The 6.5 million players of World of Warcraft inadvertently provided insight into how infectious diseases can be spread among people in the real world. Two years ago, the game introduced a new layer of challenge: players could battle a monster that infected them with “corrupted blood." For expert players, this disease was no more dangerous than the common cold. However, less-experienced players were vulnerable to a disease that could easily kill them.

The infection spread through the game with astounding speed. As in a real-world epidemic, interspecies transmission and frequently-traveling players were two factors that accelerated the rate of infection. The game's developers tried but failed at quarantining the disease. As a last resort, they reset the game's servers, and this stopped the epidemic.

Epidemiologists have watched this story unfold with keen interest. As the current issue of The Lancet points out, this

marks the first time that a virtual virus has infected a virtual human being in a manner even remotely resembling an actual epidemiological event....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.

World of Warcraft public health epidemiology epidemic