Malkavia

Malkavia is an illness affecting Kindred that causes serious mental illness. It is not clear how the disease spreads, but once it begins to spread it can rapidly fracture the Kindred society of any city. Those affected by the illness, called Malkavians, are seized by hallucinations and delusions. In the past they may have been tolerated or even welcomed in vampiric courts, occupying a niche somewhere between jester and oracle, but in modern nights they are typically ostracized, even killed to prevent contagion.

There is no known cure for Malkavia. When an outbreak becomes known, neighboring courts are likely to enforce a quarantine of the affected area until the disease has run its course.

Background
The illness is clearly a reference to the Malkavian clan from Vampire: The Masquerade.