Shakes

The shakes was the name of a disease.

Effects
The shakes caused the diseased person's body to shake with uncontrollable fits, tremors, twitches accompanied by a loss of agility. Its contagions spread via contact and the incubation period was a mere one day.

History
By the 14 century, a spell called contagious fog had been developed in the Underdark that caused victims of it to be infected with the shakes without any incubation period.