I came across an interesting article about diseases in fantasy fiction, and that got me thinking about how rarely illnesses come up in my work. So far, I've had one story where disease played any real role, and it was basically a reason for the main character to be alone in the woods gathering herbs (she was a mage and a village healer, and her magic couldn't help with the illness in question). I also have a vague storyline featuring a monarch character, based on Baldwin IV of Jerusalem, who suffers from leprosy but I haven't written anything about him yet. So what role does disease play in your work? Is it something mostly left in the background, or does it have a major effect on your plot? Does it ever influence your world on the same scale as real world diseases have influenced the course of history?