[Name] Corprus [Source] The Elder Scrolls III: Morrowind [Symptoms] 
Corprus causes incredible mutations in humanoids, but it is an almost non-communicable disease. People infected with blight are often sent to a special institution called the Corprusarium, which was made for researching corprus. Corprus is caused by the volcanic ash that emanates from Red Mountain, but, as a positive side effect, grants 100% disease immunity. The only known antidote is proven to destroy corprus, but ends up killing the victim as well. However, the player is able to take the antidote without any adverse effects, presumably because he is the reincarnation of the demi-god Nerevar.