What you are about to read is probably the strongest evidence, currently available, to support the importance and unique appeal of MMO games.
Blizzard recently added the Zul'Gurub instance which contains the God of blood, Hakkar; who has a rather handy debuff, the pleasantly named, Corrupted Blood. Once used it causes 250-350 damage and infects nearby players. For all intents and purposes those infected carry the disease with them and can also pass it on to other players. Anyone level 50 and under is pretty much an instant victim of the disease while the problem has spread so much that Blizzard has tried quarantine measures against infected players. These however, have failed and new plans are being drafted, our guess is Blizzard may have the CDC on speed-dial.
The pleasantly surprising news is that the developer is currently resisting the urge for a quick-fix patch solution and is treating the world it created with respect. This is a perfect example of how a completely non-scripted event can gain such momentum that it can become a major game-world event. The plague has become such a talking point that community websites devoted to it have now popped-up
One interesting suggestion by WoW players was that Blizzard should refrain from completely eradicating the disease but that they should ...patch it to take level into account for the damage applied (just so its not one-shotting people), and leave it in the game. Its a very interesting surprise to see something like this.
Whichever way you look at it this epidemic is one of the most interesting events to have come up this year in gaming and it's unintentional.