Miteralis is referred to in a scan taken in Metroid Prime. It is said to be a sentient gaseous Global Exterminator virus that has infected the planet Bilium within the Ooromine System. Circumstances seem to indicate that the virus is artificial and was intentionally introduced into the environment of Bilium, but this is an unconfirmed statement. Without a doubt, this virus will render the surface of Bilium completely uninhabitable, and destroy all of the native life. The infection of Bilium is the only known case involving the use of this global virus.
Based upon the fact that these gaseous entities are composed of, if they are like Earth viruses, a multitude of microscopic individuals, they may share a hive mind where the components of the many form one sentient conciousness. However, little to nothing is known of the virus, or the circumstances having to do with its infection of Bilium, though based upon it being called an "Exterminator virus", it may possible kill everything it comes in contact with.