A while back they had a live event called the plague. It was an actual, contagious plague that players and NPCs caught. While it did nothing to your stats, fighting abilities, or crafting, it did turn you a funny shade of green and make you perform various "sick" animations -- coughing, holding your stomach, etc. One infection lasted an hour and a half (they might have shortened it later, but I can't recall). I do know they made it a little less catching eventually...for a while you couldn't visit a city without getting sick. Cure Noxious could cure it, but you'd always get it again. The ultimate cure was a big quest that involved alchemists and a final lvl 50 raid zone. If that quest was done, the plague was cured on that server. Eventually, Sony took the plague away from the last few servers that had it, because it had outlived its fun and was just annoying players.