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A Rustlung patient at Jacinto Medical Center.

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

Rustlung was a fatal lung condition caused by long-term exposure to Imulsion vapor. It was common in Imulsion miners and others who worked with Imulsion, as well as residents in an area of high Imulsion pollution. Inhaled Imulsion fumes progressively builds up in the lungs and leads to inflammation and infection. Rustlung was also an early stage of Lambency.

Epidemics were caused during the initial mining of Imulsion and the evaporation of Imulsion during the Locust War. Rustlung later resulted in a pandemic in 14 A.E. following the rise of Imulsion vapors on the surface. The pandemic ended in Bloom, 17 A.E. following the deployment of the Imulsion countermeasure. However, despite being Imulsion-based, Rustlung's effects still remained in some humans.

Extensive research has been put into the study of Rustlung. Some of the research involved unethical experimentation that was classified by the Coalition of Ordered Governments. Genetic research on the children of Imulsion-poisoned miners by Dr. Niles Samson eventually led to the creation of the Locust Horde, a race of mutated humans that resided underground until emerging and waging a war against the human race, nearly resulting in their extinction.

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, muscle pain, weakness, hemorrhaging, fever, headache, loss of speech, hair loss, accelerated nail growth, eye discoloration, sterility, nausea, vertigo, insomnia, paranoia, and increased aggression.


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


Factors that predispose to Rustlung include 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 an immediate damage to the cells. Cellular stress and degradation occurred, while the symptoms then set in after adequate exposure. Some of the symptoms could cause death, and thus be prevented with various forms of treatment, but the progress of Rustlung would eventually lead to death due to the metastasis of damaged cells in the body.

When Lambency jumped the species barrier to humans, Rustlung was simply the first stage of Lambency. The host would eventually die, but after acting as a vector for the the disease. Imulsion corrupted the brain, colonizing the host to infect or kill any unaffected organisms. These Lambent Humans would have accelerated speed, strength, agility, and resilience. In time, the cartilage would burn off the skin turned necrotic, followed by mutation of vestigial limbs. In death, their bodies would erupt in spores in order to reproduce.

Due to the cell stress and degradation caused by the Imulsion, in some cases where the damage was too severe and irreversible, Rustlung became a kind of cancer that was inevitably fatal to those not cured by the Imulsion Countermeasure Weapon even with Imulsion, the original cause of the disease, extinct.


The only known treatment for Rustlung is radiation therapy. The treatment is formally known as the Imulsion countermeasure, which expels waves of targeted-radiation levels aimed at only destroying the DNA of Imulsion, thus killing the cells colonized by Imulsion. However, side-effects are severe depending on the progression of the disease. If the patient is experiencing fever or intense muscle pain, they are at risk. The countermeasure is fatal for patients whose majority of cells have been colonized by Imulsion, resulting in cell degradation and death.

Other medications can remedy the symptoms and extend the lifespan of those diagnosed, but Rustlung would remain a progressive and fatal condition. Research conducted by Dr. Niles Samson confirmed that exposure to Imulsion does immediate damage to the body - causing cell stress and degradation followed by metastasis. The patients who still suffered from Rustlung after the Imulsion countermeasure had suffered irreversible damage to their bodies, which caused the condition to progress and thus remain fatal to them.



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 to rustling and Imulsion, 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.


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.

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.


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