During the time of Yōji Itami and the rest of the resource scouting teams visit to Crety, the city was affected by an epidemic of a deadly disease carried by windborne sand and spread by the Sirocco Wind. Female members of the population seem to be the only ones susceptible to the worst symptoms, and suffer from a 50% morbidity (sickness) rate in the city. Of those 50%, there is a 70% mortality rate. The illness appears to be contracted by inhaled sand, and onset of symptoms is very sudden, as seen when Lelei La Lalena suddenly collapsed after contracting the illness. The villagers of Crety disposed of the bodies of female victims in the Arrun Labyrinth.
Initial symptoms include high fever and inflammation of the throat and lungs. The disease is known to be treatable with an anti-inflammatory medicinal plant known as the Rokude Pear, provided the treatment is administered before death and subsequent reanimation. The infection is known to affect both humans and other species, as evidenced by an infected Cockatrice found in the Arrun Labyrinth.
After death, the body will not decay but rather reanimated into an at least outwardly life-like state, referred to in the Special Region as "Death's Makeup". Those in this state of being can be identified by their glazed-over, "dead-looking" eyes, as well as their darker colored blood. The infected possess greatly reduced intellectual capacities, single-minded pursuit of uninfected humans with the intent to infect or kill them. Once reanimated, there is no known way to return the infected to their pre-mortem state- the only means of neutralization is to kill them. Infected individuals are highly resistant to damage and can only be killed by decapitation or destruction of the brain or by extreme trauma to the entire body, such as a grenade blast. The effects can differ, depending on who was infected.
When humans, at least women, are infected they would move sluggishly and would act indifferently to their surroundings, regardless if they are being attacked or not. When a Cockatrice was infected, it was shown to be capable of reacting quickly to its surroundings and moved as if it was still perfectly alive. Combat-wise, the Cockatrice apparently gained benefits from the infection where it gained immunity to pain, as neither a grenade nor firearms were capable of slowing it down and can only be killed when decapitated. The only species that seemed to have been able to resist the infection was the Minotaur. One such creature in the Arrun Labyrinth was able to feel pain despite having eaten a number of infected cadavers.
This state is believed by inhabitants of the Special Region, including Rory Mercury and Yao Ro Dushi to be an instance where a departed soul is trapped within the the dead body and the act of killing an infected as "liberating the soul", allowing them to pass on to the afterlife. Rory considers the plague a sign of Hardy not doing her job.
The actual origin point of the outbreak was revealed to be the very location used to dispose of the bodies of the dead, the Arrun Labyrinth. It was secretly the location of an experiment in immortality gone horribly wrong. After Yōji Itami and Yao Ro Dushi rescued Rory from the innards of the Minotaur in the Labyrinth, they burned the body of "patient zero" of the outbreak, which is shown to be a hideous female creature, ending the outbreak. All survivors of the outbreak were subsequently cured using Rokude Pears found within the Arrun Labyrinth.