Glitches are the results of infected persons of the outbreak from five years prior to the CTC storyline. A cure for glitches was in the works at the Washington State Lab.
Glitches resemble the modern depiction of zombies -- dead but undead, caked in blood, covered in wounds, and having sickly green skin. Their eyes are full white with two lines crossing over each other (similar to a "+" sign) instead of pupils and look exactly as their name suggests: pixelized and altered with almost indecipherable speech. At the same time, glitches are often seen with plants sprouting from their bodies, an interesting compliment to the tech-y infection. An early dialogue of a newscaster reports glitch symptoms " ... as excessive coughing, aggressive behavior, agitated skin, or muddled speech."
When a person has become infected, they turn into glitches. They become aggressive and begin to attack humans, killing them and spreading the infection. Despite being undead, they have the ability to communicate although their speech is greatly impaired and broken.
At the current point of the story, there is no cure to the glitch infection, however Lillium states that there is a way to "kill" the infected.
"The only absolute way to 'kill' them forever is... uh, fire. You have to burn them until they're nothing but dust. ... Any wound that isn't made by fire gets replaced by plants immediately ..."