Tellurian Plague
Borne by spores exuded from the Devouring Earth monstrosities, the constantly mutating (2) Plague exerts a malign influence upon the minds, and ultimately the bodies, of those infected. For the safety of the Empire and for the plague victims themselves, Marcus Cole has established the Behavioral Adjustment Facility to house the afflicted, to treat the disease, and also to devise a cure. Unfortunately, though Neuron is working on a cure right now, the only vaccine he has discovered so farcombats only the first stage of this deadly illness (4), so a definitive cure has yet to emerge, and until that wonderful day arrives, the guests of the B.A.F. are forced to remain sequestered within. (1)
The Clockwork are programmed to respond to this menace as well, creating safe zones and conducting arrests in case of an outbreak of the Plague.(3)
Sources
1 - Imperial City Official Background
2 - Part Two: A Matter of Recognition from Neuron
3 - Praetorian Clockwork Official info
4 - Neuron Official Bio