Simple, really.
Real life diseases and illnesses, in addition to anything you could find on a D&D or Pathfinder wiki, in addition to whatever could be thought up and put it in at the behest of imagination. I didn't really focus a whole lot on this area, seeing how there were already plenty in existence that I could modify the severity of or mix and match the aspects of.
There is one unique sickness which I have come up with, and it is the most powerful and most deadly affliction on the planet. Rot-Loj-i. This is one of the few afflictions powerful enough to affect a fully matured Draconic (pretty much one of the most hardy and durable creatures on the planet) and kill them. It roughly means "Fire Rot", and it's main symptoms are dramatic increases in body temperature and excruciating pain throughout the entire body. A physical sign of the affliction is a fiery ring will begin to appear around the very edges of the whites of the eyes, and slowly begun to close in on the pupil as the affliction progresses. The closing in of this ring signifies the symptoms above, increasing in severity, as well as an ever increasing violence and madness. It attacks the body in its entirety, mind, body, and magic. By the time the disease reaches its final stages, the afflicted creature will become a completely mindless killing machine, their body temperature off the scale, in constant agony, seeing hallucinations in the forms of worst nightmares, and adrenaline glands and such working overtime. Most creature's bodies give out long before this stage, but if they made it this far they won't have long left. They will be faster, stronger, more merciless, and more violent than ever before, along with nigh immunity to pain. Their body will only be able to survive the stress for around an hour, but it will be the longest hour of their lives, and they will quite literally attack anything everything. It is unknown how this affliction came to be or how it is caught or spread, and it is extremely rare. It's not known to be contagious.
The normal ones and the ones from the wiki are generally much, much worse than they would be elsewhere. Generally even a minor sickness is deadly. If someone is sick with a severe enough disease of
illness that is contagious, the Angelics have few qualms with exterminating them to prevent its spread. However, that would only be for something they determined to be plague level, and was actually powerful enough to spread to them as well.