The type are known as Lost, occasional seizing of control is called Possesion often semi permanent. Madness results from internal conflict between the Host & an addition & is a punishment of inept behaviour by an Intruder.
Space Zombie
Holly a Media Geek aquaintence indicated that proximity of Kin, usually Neighbours causes full Possession. The kind you might Shoot with Weapons & Ammo found lying around in a Derelict Duilding in worst case Senario.
