

Infection can be spread through biting a victim. However some have had resistance to the infection, notably Ellie she hasn't turned despite being infected for a year though her rash from the bite mark has worsened slightly. The host will then go through four different stages of infection: Runner, Stalker, Clicker, and Bloater each stage is more dangerous than the last. The military at one point bombed areas outside the Quarantine Zones to kill the infected and executes anyone suspected of infection on sight.įor humans that have been exposed to a mutated strain of Ophiocordyceps Unilateralis, the fungus attacks the brain and begins to alter the behavior of its host.

Those who are clear of infection are ordered by martial law to reside within a Quarantine Zone. They believe they can create a vaccine through study of the fungus and its hosts, one of the last organizations to do so. The Fireflies – a militia group formed in response to military oppression – have conducted a mostly futile war against the barely-functional government. As the vicious fungus has taken hold of the majority of the population, the worldwide pandemic causes the total breakdown and destruction of society through widespread violence the failure of martial law to contain the outbreak, the military's increasingly violent efforts to censor information, and the near-extinction of humankind. Public reaction to the Infected has been catastrophic. Eventually the fungus kills its host, and will then grow out of the host's body to spread spores. This erases their memories and drives them insane, modifying their instincts to seek no goal other than spreading the spores to others. The fungus infects the human brain, growing mycelium inside the brain tissue and killing the brain's cells. The fungus reportedly originated in South American crops various newspapers in the prologue support this claim. The Infected are the result of a sudden outbreak of a mutant Cordyceps fungus that now affects human beings as opposed to merely insects.
