Nanocloud

A nanocloud was part of the protection system for the Dalek Asylum. It used nanogenes to convert non-Dalek individuals who penetrated the force field into Dalek puppets. The conversion would work on living or dead flesh. For those whose minds were not decayed after death, it could resurrect them; otherwise, the subject would become the equivalent of a zombie. Time Lords were immune to the effects of the nanocloud. The Daleks could also give individuals protective bracelets that would stop them from being converted when exposed to the nanocloud. (TV: Asylum of the Daleks)

Even if the nanogenes invaded a subject's body, the conversion process could be resisted or even undone on some level if they emotionally fought against the reprogramming. (TV: Asylum of the Daleks, The Time of the Doctor)