1) Fully treatable and low chance of damaging organs
2)Treatment only prevents escalation of infection to 3, injured organs have moderate chance of being damaged, healthy organs have low chance
3)Treatment futile, all organs take guarenteed damage, the dwarf is going to die.
Well, with this choice we either have a benign disease (1), or the guarantee that the dwarf will die sooner (3) or later (2). Something more pondered, from a scale from 0 to 10 :
0 - Healthy dwarf. No infection whatsoever.
1 - Benign infection. Cannot evolve to greater disease. The dwarf is tired or need to eat or drink more often, and recover by himself after a short period of time.
2 - Very small infection. Same symptoms as above, but the dwarf can either (depending on his toughness attribute, maybe) recover without intervention or go to level 3.
3 - Small infection. Same symptoms, but more annoying : The dwarf is tired when doing almost every hard manual jobs (mining, woodcutting, fighthing, etc). The disease cannot (or with a very low chance) disappear by itself, it has to be treated. Hopefully, it is easily treated provided you have access to basic medicinal plants.
4 - Medium infection. The dwarf is now tired after every job. The disease HAS to be treated, and WILL evolve to a worse situation if left untreated.
5 - Incapacitating infection. The dwarf cannot work at all, and is most likely in his bed. The infection will evolve quicker if the dwarf can't have access to a bed, plus he will move slower. Tougher and longer to heal, but still easy with the required medicine.
6 - Bad infection. If the dwarf hasn't access to a bed, he will fall on the ground and won't be able to move. Some organs start taking damage. Harder to heal.
7 - Very bad infection. The dwarf may fall unconscious if is toughness attribute is too low. Organe take more damage and faster. If you haven't access to advanced healing devices, the situation is critical.
8 - Severe infection. The dwarf is more likely unconscious now. Organs start to damage themselves faster. Bleeding can occur. Will require immediate assistance with the best medicine and physicist available.
9 - Critical infection. The dwarf is in a very difficult situation. Organs very damaged, heavy bleeding etc. Even with the best healing available, the dwarf may die.
10 - Too late. The infection has spread to the whole body, and is too strong to be treated even with the best medicine and doctor of all the civilization. Death can not be avoided, and will usually occur in a few days.
If left untreated, the dwarf may recover (1-3 stages) without intervention, but after the situation will worsen faster and faster with each level.
Additionnaly, theses symptoms can appear, worsening the situation (accelerating the spread of the disease and giving bad toughts) :
- Vomiting (from 4 to 10).
- Lost of counsciousness (from 7 to 10)
- Bleeding (from 8 to 10)
Additionally, the dwarf could be paralyzed, but since it's a "brain" condition...
The recovery time will be longer and longer for each situation, because you can't recover instantly (ie, going to 6 to 0), but rather have to go from 6 to 5, then from 5 to 4, etc., meaning that a dwarf will need healing to at least the level 3, although it will be more cautious to heal it up to level 1.
Additionaly, the disease spread speed will be influenced by theses modifiers :
- Thoughness of the dwarf.
- Healing conditions (bed ? hospital ? noise ?)
- Morale of the dwarf and personnality traits (happy and combative = improved recovery chances)
And of course, the quality of medicine and the skill of doctors. There's a lot to do on this topic...