Not much is known about its history or development, but Lt. Muldoon stated that he and his team got infected in Pakistan. Abby was selling DC2 to Lt. Muldoon; it appears as if the DC2 made its way to the U.S. for study or possibly creating more.
Possible Second Outbreak
More DC2 was kept under the Military Base , when the detonation occured, it is likely that the DC2 had escaped into the enviroment.
Means of infection
The DC2 is airbourbe, so most people are infected simply by breathing the contaminated air. Those who were contaminated by it became zombies and bit others, infecting them. However, if the bitten part of the body is amputated before the bacteria takes over, the infection is gone. Contagious blood coming into contact with bare skin doesn't seem to infect others.
The sickos are very disgusting in appearance. They are covered in pimple-like bumps all over their face and body, resulting from the DC2. They walk very slow and do not seem to run but are very strong in their arms, teeth and biceps. They can pick a man up and throw him and rip a body part off in seconds. They are fast eaters, as well.
The DC2 virus is airborne, anyone within its reach was suppose to get infected. However, a few people are not affected by the virus itself. For those unaffected by the virus, it wasn't specified if once bitten one turns into a Sicko.
main article: Sickos
TreatmentsAs told by Abby, the only treatment is a constant intake of the virus, it stops the infection from spreading; apart from this, no known treatment is mentioned.