1-30

Mild: A nasty cough, a high fever, persistent tiredness or pain, etc. Not enough to impede the Inquisitor in their duties, perhaps, but enough to be noticeable.

31-40

Debilitating: A disease strong enough to impede the Inquisitor's ability to carry out their duties, like Eyerot or Catachan Sloughing Fever. May be lessened somewhat with the right medications or surgeries, perhaps requiring bionic replacement if the disease is severe or has progressed far enough.

41-60

Terminal: A disease that is slowly killing or crippling the Inquisitor from the inside (St Basil's Spineblight, Tyranid Spore-Cysts, aggressive malignant tumours, etc.) Its progress can lessened or even temporarily stopped, but never cured, and sooner or later it will render the Inquisitor either a cripple incapable of carrying out their duties or dead.

61-80

Xenovirus: An alien virus has infected this Inquisitor, with its xenos-born nature making it far more difficult to treat and identify.

81-99

Warp-tainted malady: A disease spawned straight from the Warp itself, with all the horrors and physically impossible symptoms that this implies. The Obliterator Virus is the most famous of such illnesses.

100

Nurgle's Rot: Wow. You're really fucked. (This Inquisitor has been infected with Nurgle's Rot and is slowly turning into a Plaguebearer. Whether they'll find the strength to kill themself before the final change or be gunned down by their allies is up to you.)