A virus was locked away in one of the Rakatan vaults on the planet Belsavis that attacked the central nervous systems of its victims, causing seizures and then death within hours. During the invasion of Belsavis, the Sith Empire unintentionally released it by breaching the containment vault, and it began to spread throughout the High Security Section. Gen'Dai were immune to the virus, but it incubated in their tissue, turning them into carriers.