The Movellan virus was developed by the Movellans to attack Dalek casings and tissue. Its effects were immediate and devastating. Symptoms included loss of motor control and expulsion of a whitish, foamy substance from vents and seals in the Dalek's casing. The infrastructure of the Dalek Empire was so damaged by the virus, the empire broke into factions and fled to distant parts of the universe to avoid infection and find a cure.