The following diseases blend the traditional style of disease progressions. Each of these diseases progresses through a series of stages, from carrier to terminal, and each stage comes with its own horrifying symptoms. The DC listed for each disease is a baseline for the most common form of the disease, but higher-DC strains of these diseases exist, especially in the vicinity of disease-bearing monsters and plague-worshiping cultists.
These diseases do not have onset periods. When the affected creature fails its initial save and becomes infected with the disease, it immediately moves into the first stage of the disease, which is carrier, though it doesn’t suffer the disease’s effect. After this, the affected creature attempts subsequent saving throws at regular intervals, defined by the disease’s frequency, just like any other disease. Whenever the affected creature fails a subsequent saving throw against the disease, it suffers the disease’s listed effect and also moves to the next stage of the disease (progressing from carrier to early, early to moderate, and so on). As long as the affected creature remains diseased, it suffers all of the effects listed for its current stage, as well as the effects of any previous stages. When the affected creature reaches the terminal stage, it can no longer fulfill the cure condition without magic; most creatures don’t survive long at this stage.
Whenever the affected creature fulfills the cure condition listed for the disease, it moves to the previous stage of the disease. If this would cause it to move to a stage prior to carrier, it is completely cured of the disease. Any effect that would normally completely cure the affected creature of a disease (such as a remove disease spell) similarly moves the affected creature to the previous stage of the disease instead.
Several of these diseases impose certain conditions at various stages. These conditions can’t be cured as long as the affected creature remains at that stage or a worse stage, even by effects that would normally be able to do so. These effects typically end automatically once the creature is cured of the disease or moves to a less severe stage. Only immunity to disease can prevent these conditions; no other immunities apply against these conditions. Occasionally, a disease might even have an effect that is permanent, and persists once the disease is cured. In these cases, the effect’s description states what measures (if any) can undo the effect, but these measures are generally effective only once the disease has been cured.