How does getting bed rest interact with the disease rules from Pathfinder Unchained?
I find the text in the relevant section to be ambiguous; it first mentions diseases, then poisons, and then bed rest. Because of this ordering, it is not clear whether the bed rest section applies only to poisons, or to both sections (emphasis mine):
In general, whenever a victim fails a saving throw against her affliction, she moves one step further down the progression track, gaining the effects of the next state and keeping all previous effects, until she reaches the end state. If she's afflicted with a disease, she moves one step back toward healthy whenever she fulfills the conditions in the disease's Cure entry (usually by succeeding at one or more saves). Once she reaches healthy, she is cured. Poisons work differently—fulfilling the cure condition removes a poison from the victim's system, but she remains at the same step on the track and recovers gradually. (Treat a poison that has exhausted its duration in the same way.) For every day of bed rest (or 2 nights of normal rest), a victim recovers one step; this recovery is doubled as normal by Heal checks, and tenacious poisons might require a longer recovery period.
If the section does apply to diseases, I am further confused by its power. Most diseases - even really terrible ones such as Bubonic Plague - call for saves to get worse once per day. If bed rest is able to heal one or two stages once per day (assuming perpetual rest, without or with a healer respectively) and the disease can only worsen at most once per day, then wouldn't it become impossible for the disease to ever get worse while resting?
Bubonic Plague Type disease, injury or inhaled Save Fortitude DC 17 Track physical; Frequency 1/day Cure 2 consecutive saves
Similarly, if bed rest is not allowed for diseases, then it makes no difference if you rest or not while sick, which is also unbelievable. Both possibilities seem weird, making it difficult to judge the actual intent.