Protoss are supposedly immune to infestation, due to protection from the fortitude of the Khala or powers of the Void, as well as an inherent genetic incompatibility between the two races. A sign of infection in a terran The virus mutates extremely rapidly, making the possibility of a cure seemingly impossible, though some serums are able to slow the spread of infestation. The victim usually loses most of their intelligence and sanity, as their mind becomes consumed by the zerg.

An infested marine An infested terran is created when a terran is infected with the zerg hyper-evolutionary virus.