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"Rustlung, Imulsion sickness. Cases have been popping up all over since the Lightmass Bombing. Sure is a horrible way for a warrior to die. They say it's not [contagious], but I would keep my distance."
—Cpl. Tai Kaliso explaining Rustlung to Cpl. Dominic Santiago.

Mercy resident with Rustlung.

Rustlung was a respiratory disease caused by long-term exposure to Imulsion fumes. Common symptoms were productive cough, labored breathing, fever, bleeding, chest and joint pain.

The disease was common in Imulsion miners and those who worked in refineries, as well as residents in an area of high Imulsion pollution. Inhaled Imulsion fumes progressively built up in the lungs and led to inflammation and infection. The condition was incurable, and life expectancy ranged from several months to several decades depending on the amount of Imulsion exposure and treatment. Rustlung was later discovered to be an early stage of Lambency.

Extensive research was put into the study of Rustlung. Some of the research involved unethical experimentation on the children of Imulsion-poisoned miners at the New Hope Research Facility by Dr. Niles Samson that was later shut down and classified by the COG. The project eventually led to the creation of the Locust, a race of genetically altered humans. Epidemics occurred from the initial mining of Imulsion during the Golden Age and Pendulum Wars, and from the evaporation of Imulsion during the Locust War. Rustlung later became a pandemic in 14 A.E. following the rise of Imulsion pollution on the surface. The pandemic ended in 17 A.E. following the deployment of the Imulsion countermeasure.

Signs and Symptoms

People with Rustlung often had productive cough and rust brown colored phlegm. Other symptoms included trouble or labored breathing, chest pain, joint pain, weakness, hemorrhaging, headache, loss of speech, hair loss, accelerated nail growth, eye discoloration, sterility, nausea, vertigo, insomnia, paranoia, and increased aggression.


Rustlung was caused by prolonged exposure to Imulsion, usually in the form of fumes.


Factors that predisposed to Rustlung included working directly with Imulsion or living in townships that were located near Imulsion mines and refineries. Among the first cases of Rustlung were miners of Imulsion and their families who were exposed and began suffering from "Imulsion-poisoning."

In 14 A.E., an epidemic of Rustlung occurred among people living in Timgad. This was due to the Lightmass Bomb evaporating the Imulsion in the Outer Hollow during the Lightmass Offensive, causing a pollution of Imulsion fumes in the city. Most of those infected were transferred to Jacinto City for treatment.

By 17 A.E., during the Lambent Pandemic, fruiting bodies of Imulsion called Lambent Stalks would emit Imulsion fumes, similar to fungus spreading parasitic spores, in order to spread the disease. At this point in the epidemic, Imulsion fumes could occur anywhere, and nearly all humans were in the early stages of Rustlung.


Until Lambency evolved to humans, the prognosis of Rustlung was usually death. When exposed to Imulsion, there was immediate damage to the cells. Cellular stress and degradation occured, while the symptoms appeared after adequate exposure. Some of the symptoms were lethal and could be prevented with various forms of treatment, but the progress of Rustlung was terminal due to the metastasis of damaged cells in the body. Life expectancy varied depending on Imulsion exposure and treatment, ranging from several months to thirty years.

When Lambency evolved to humans, Rustlung was the first stage of Lambency. The host would eventually die, but after acting as a vector for the the parasite. Imulsion corrupted the brain, colonizing the host to infect or kill any non-infected organisms. These Lambent Humans gained accelerated speed, strength, agility, and resilience. Cartilage would burn off the skin and turn necrotic, followed by mutation of vestigial limbs. In death, their bodies would erupt in spores in order to reproduce.


There was no cure for Rustlung. Some patients received medical treatment to remedy the symptoms and prolong the patient's life expectancy. Among these treatments was the Immune System Booster created by the Nedroma Health Institute in Vasgar, but it contained devastating side-effects. Preventative treatment was possible through radiotherapy, but only before Rustlung reached a critical stage.

Because of the Imulsion countermeasure, no new cases occurred after 17 A.E., but those diagnosed with mild enough cases to survive the radiation wave continued to suffer from the condition. As of 30 A.E., there are no known cases of Rustlung remaining.



Rustlung was first documented in the early Pendulum-era shortly after the discovery of the Lightmass Process, before scientists could study the health effects of Imulsion. The name is from the brown phlegm that is expelled by its victims, which had a rust brown color. Patient Zero was considered to be Ukkon, the child of an Imulsion miner during this time. Miners of Imulsion and their families who lived in townships near Imulsion refineries were the most affected by Rustlung. A majority of Imulsion reserves on Sera were on the nations of the Coalition of Ordered Governments. At the time, this newly-discovered, limitless fuel source would promise the Coalition to be the political and economic superpower of Sera. Due to possible political and economic ramifications if the public learned of health issues related to Imulsion mining and usage, the Coalition of Ordered Governments Department of Health, under the Monroe Administration constructed the New Hope Research Facility to house and treat the affected children of the Imulsion miners in order to discover a cure for Rustlung. The Director of the New Hope Research Facility was geneticist Dr. Niles Samson.

While children continued to suffer and perish from Rustlung during his research, Dr. Samson discovered possible point mutations that could benefit humans. He believed that he could use this as an opportunity to evolve humans into an immortal, superior species. Among his patients, a child named Myrrah was discovered to not only be completely immune Imulsion's ill-effects, but also gained beneficial mutations from it such as decelerated aging. Dr. Samson attempted to replicate Myrrah's immunity in the other children, but he was unable to do so. Instead, Niles utilized the possible point mutations and began experimenting in cross-species genetics. Using the DNA from the indigenous creatures of the Hollow, who he believed held genetic immunity, Dr. Samson began splicing their genetics with the infected children. However, the children mutated in a new species known as Sires. Though one of the Sires, Ukkon, retained his intelligence and even benefited from Imulsion exposure, he continued to suffer from Rustlung for the rest of his life.

While the Sires were aggressive, distempered, sterile, and genetically unstable, Dr. Samson saw them as children. However, the predatory features now within the Sires, the staff at New Hope were victims of maulings and violent attacks. Due to the attacks and unethical experimentation in the facility, several staff members resigned and leaked information to the public and government. Eventually, Chairman Monroe ordered the shut down of the facility, and all staff members, including Niles Samson, to be indicted. However, a fringe political group within the Monroe Administration contacted Niles Samson, conveying that they believed in his work and wish to see an end to Rustlung and the Pendulum Wars by any means necessary, believing Chairman Monroe to be too optimistic. This group then constructed a secret facility in the caves of Mount Kadar where Niles Samson could continue his work. Following the shutdown at New Hope, the entire operation was made classified, and outside existing information was destroyed.

Only the Chairmen of the COG were made aware of the New Hope Research Facility, incidents there, and the overall of Rustlung and other health effects caused by Imulsion. Continuing the research for Rustlung, more humane efforts were studied in the classified research facility on the island of Azura, where the top minds of Sera were relocated in order to cure Rustlung. In the meantime, the Coalition issued more safety and health protocols for the Imulsion miners and workers. Rustlung continued to spread, however, as pollution caused a decrease in human reproduction and increase in sterility. Rustlung eventually became a known condition among the mining community, as it was known that workers in Imulsion mining had a shorter life span than the average human, but were unaware of the worst of the effects.

14 A.E. Outbreak


Sgt. Jonathan Harper experiencing Rustlung in 14 A.E.

The Locust Horde, the descendants of the experiments done at New Hope, launched an attack from underground known as Emergence Day, killing 25% of the human population and launching humanity into the Locust War.

In Gale, 14 A.E., the Coalition launched the Lightmass Offensive in an effort to destroy the Locust stronghold using the Lightmass Bomb. The Coalition was successful in launching the Lightmass Bomb in the Outer Hollow near the city of Timgad, prescisely destroying Timgad Valley, but it failed to destroy the Locust stronghold, which resided in the Inner Hollow. The citizens of Timgad, however, suffered an epidemic of Rustlung as the Imulsion from the Hollow in Timgad Valley was vaporized, causing a pollution of Imulsion fumes in the city. The Gears and civilians in Timgad began to suffer from Imulsion sickness and many were transported to the Jacinto Medical Center in Jacinto City.

Rustlung--article image

A Rustlung patient at Jacinto Medical Center.

Due to the esoteric knowledge of Cpl. Michael Barrick, he revealed that the conditions he and other fellow Gears and citizens from Timgad were suffering from was Rustlung. However, those in the administrative levels of Jacinto Med such as Dr. Vivian Merriweather contributed the symptoms to vertigo and PTSD, while other doctors were skeptical of Dr. Merriweather's assessment along with close ties to the administration. The doctors were adamant about diagnosing a real condition. Unknown the them, the Coalition was still attempting to keep the health effects of Imulsion classified. Regardless, the public came to their own conclusion that there was an epidemic of Imulsion-sickness, and it became known that Rustlung was a true medical condition.

Lambent Pandemic

After a century of covering up the health effects by the COG, Rustlung became known to the public and eventually became widespread among the human population of Sera. By 17 A.E., every human had Imulsion in their cells and many suffered from Rustlung. During the Lambent Pandemic, Rustlung began to spread rapidly in Mercy and other locations near Imulsion. Lambency then jumped the species barrier once again and began to infect humans, tagged as Formers - the first known cases of Lambency in humans since the early Pendulum Wars.

Rustlung was studied by Adam Fenix on Azura and considered using targeted radiation rather than biological means to cure Rustlung and Lambency. Rustlung ceased to occur after the Imulsion Countermeasure Weapon was detonated, erasing all Imulsion across Sera including all infected cells in humans, while also killing off all Lambent lifeforms. By this point, every living organism on Sera were infected. However, those not heavily infected with Imulsion were cured of the infliction. Although there were no new cases since 17 A.E., cases still remained from before. The last known case was in 30 A.E., due to the fact that Imulsion exposure and Rustlung caused irreparable harm to the body and its cells, acting as a form of cancer.


New Hope Medical File
Patient Name: Ruth
Age: 15

Symptoms: Ruth is clearly experiencing extreme swelling in her joints and frequently cries out in pain during the night. She also exhibits rather erratic and unpredictable behavior, though this is quite understandable considering her situation and symptoms. There is a strange discoloration in her eyes, and her breathing often sounds labored. Her nails grow at a faster rate than normal, though her hair grows at a markedly reduced rate. I'll keep trying to find some type of medication to alleviate her pain without adversely affecting our studies.

Dr. Niles Samson

Patient Analysis: AX-331-2
Prior to loss of speech, the subject complained frequently about joint and lung pain, as well as agonizing headaches.

Subject's exposure to Imulsion was severe even before testing began. Once Rustlung had metastasized throughout the Subject's body, death came quickly.

Imulsion's effects lead to intense and immediate cell stress. But other cells undergo point mutations that could be considered beneficial. Studies will continue.

Dr. Niles Samson

Patient Analysis: EV-184-9
EV-184-9 has been exposed to Imulsion levels hitherto known - without exception - to be fatal. Yet she displays no detectable cellular degradation at all. Quite the opposite, if anything.

We have decided to isolate and observe EV-184-9 closely, twenty-six hours a day, while continuing to administer a daily dose of concentrated Imulsion. We tell her it's her medicine and she smiles while she takes it. She is quite eager to be helpful.

Dr. Niles Samson

Patient Analysis: RK-619-4
RK-619-4's final transformation occurred roughly eighteen hours before death. Quite disappointing, as the subject's cells had initially benefited from Imulsion exposure nearly as much as Subject EV-184-9's.

It is time to face a hard truth. EV-184-9's response to Imulsion exposure may be entirely anomalous. And Dr. Torres has just informed me that EV-184-9's T cells appear to be particularly responsive. He believes her body is now aging at a pace roughly half that of a normal girl.

Dr. Niles Samson

Ambulance Driver's Log
Driver: Wayne Mitchell
Route: Timgad/Jacinto

Patient #1: 33 yr. old male
Symptoms: Coughing up blood & brown mucus, nausea, minor bleeding from ears

Patient #2: 21 yr. old male
Symptoms: Nausea, coughing up blood & reddish-brown mucus

Patient #3: 36 yr. old female
Symptoms: Unconscious, blood & reddish-brown mucus coming from nose & mouth

Patient #4: 24 yr. old male
Symptoms: Coughing up blood & dark brown mucus, complaining of severe chest pain & trouble breathing[1]

Doctor's Journal - Dr. Nicolette Shannon
Dr. Merriweather mentioned that she's seen numerous patients exhibiting similar symptoms, even paranoia and aggression, but she appears to be less concerned than the rest of us. I'm starting to wonder whether her close ties to the COG administration could be affecting her judgment about the patients' welfare. Going to follow up on this with the director tomorrow.... If we aren't taking care of our soldiers, who will?[2]

Jacinto Medical Center File - Jonathon Harper
Patient Name: Jonathan Harper
Occupation: Sergeant (Echo Nine), COG Army
Age: 29
Height: 1.9 m
Weight: 91 kg

Patient is a 9-year veteran who has recently experienced vertigo, persistent cough, and insomnia. Was stationed in the Timgad area for 2 months after Lightmass offensive, then assigned to Jacinto perimeter patrol last 4 months. Symptoms began about 1 month ago. Physical and diagnostic evaluation showed no chronic illnesses and no signs of bacterial infection. Prescribed a medium-strength antihistamine, released patient, and gave clearance for further duty. Expect a full recovery, with no side effects.

Dr. Vivian Merriweather[2]

Known Patients

Behind the Scenes

  • Rustlung strongly resembles the real-world disease known as Coalworker's pneumoconiosis or black lung. It was a condition caused by long-term exposure to coal dust and was common in coal miners and others who worked with coal. It was prevalent during the 1950s and 1960s, prompting coal miner unions for protection and advocating for the Federal Coal Mine Health and Safety Act of 1969



  1. Gears of War 2: Act 1: Tip of the Spear: Welcome to Delta
  2. 2.0 2.1 Gears of War 2: Act 1: Tip of the Spear: Desperation