Kharaa Bacterium

The Carar is a bacteria that seems to be all over Planet 4546B. It is described in the Degasi PDAs as "part of the ecosystem". It is suggested that the Degasi survivors were infected at some point, as stated by Bart Torgal.

Afflicted creatures will be identifiable by the small, glowing cysts on their body.

Warpers will attempt to kill infected creatures once their infection passes a certain level.

The player is infected with the Carar, though it only becomes noticeable when the player reaches the Lost River Precursor Base. There is scanner in the Precursor Ground-To-Air Weapon System that prevents the door to the control panel opening if the life form is infected.

If an infected creature is placed inside an Aquarium or Alien Containment, the creature will infect the rest of the creatures inside soon after. However, this is purely cosmetic and has no impact on the gameplay.

Trivia

 * The Virus is loosely based off the appearances of the Kharaa from Natural Selection 2, as the Kharaa have similar looking cysts on their body.