Prior to the Clone Wars it struck the population of Jabiim to which the Galactic Republic did not send aid. It was used as a biological weapon by the Confederacy of Independent Systems during the height of the Clone Wars. General Grievous ordered Separatist forces to release the plague on the Weemell sector, wiping out the entire Human population, including the clone troopers of the Grand Army of the Republic. The sector was rendered uninhabitable in a matter of months.
The plague was found in three different types: Brainworm Rot Type A, B, and C.