Disease

Spelunker's Itch
Sir Winden Nek-Smith of the Gus Kingsguard pioneered a cure for Spelunker's Itch involving the flesh of shrieker mushrooms.

Oobort's Necrosis of the Skin
Live dire maggots can be used as a cure for Oobort's Necrosis of the Skin.

Sifinacova
Only elves and those of elven descent are affected by Sifinacova, a terminal illness for which there is no known cure. It is not contagious, but it might be genetic in origin.