Disease

Diseases are negative conditions that are contracted from enemy attacks, curios, traps, and occasionally as a random quirk at the end of a dungeon. You can only get a disease at the end of a dungeon if your hero's resolve level is at least 2. If it is, the chance of getting a disease is 32% - 0.33 * disease resist but at least 5%. Althought most of the diseases are harmful, Rabies is quite beneficial because it grants +15% DMG while only reducing -10 ACC. You can get them while fighiting Rabid Gnasher relatively easily because they are not dangerous. They last until removed. They can be cured in the Sanitarium for some gold (where there is a chance of multiple diseases being cured at once depending on upgrade level) or by using the right camping skills from the Grave Robber or the Plague Doctor (which will cure all the diseases on the targeted hero).

A hero can have at most 3 disease at once, if they acquire a new one it replaces an old disease picked at random.

Trivia
The Carrion Eater and Crone have the only effects that increase Disease chance at higher levels.