It has already infected millions, and if you get into close enough contact, you will catch it too.
There's no cure. All you can do is arm yourself with a dose of civility and stay as far away from the sickness.
But, sadly, even if you join the mannered lepers hiding behind genteel walls, it's just a matter of time until the malevolent lava from Mount Vitriol buries you and everyone else in its path.