What we know about the disease:
It is magical and mundane in nature.
It has only been contracted by those that are in the merchant guild that have been in contact with the ore.
It is not easily contracted.
It has not affected any of the leaders of the merchant guild.
It has been tracked down to the mine in the mountain of Idar.
It effects folks that cast spells (or spell-like powers) or use magical items that cast spells.
Healing potions will heal the damage from using magic!