After the COVID-19 pandemic, the world became familiar with a dreaded syndrome of chronic illness: long COVID.
Long COVID is a systemic condition associated with fatigue and brain fog, among dozens of other possible symptoms. Having received institutional validation this year, in the form of its own ICD-10 code (U09.9), long COVID is paving the way for a better understanding of chronic metabolic injuries triggered by a prior exposure to a biological agent—the acute infection is long gone, yet the sufferer remains enmired in disease.
A period of respiratory exposure to indoor dampness and mold causes a syndrome that is mechanistically similar to long COVID. Even after leaving the exposure, there may be persistent fatigue and brain fog. Neurological injury, particularly neuroinflammation, causes symptoms virtually identical to post-concussive syndrome. Hormonal injury can cause menstrual abnormalities in women and low testosterone in men.
There can be a range of immune injury including chronic inflammation, immune suppression, and autoimmunity. Collectively, these and other forms of immune disturbance can be described as immune dysregulation. The symptoms of long COVID have been long familiar to clinicians treating mold-exposed patients, particularly those who focus on a condition known as Chronic Inflammatory Response Syndrome.
Chronic Inflammatory Response Syndrome Defined
Chronic Inflammatory Response Syndrome, known as CIRS for short, is a chronic medical condition that develops after occupying water-damaged buildings.
As in long COVID, not everyone with an exposure becomes ill long-term. One of the key determinants is genetic susceptibility. In CIRS, the chance of developing chronic metabolic and immune injury rises substantially if there is a susceptible Human Leukocyte Antigen. The HLA gene, on chromosome 6, is an important modulator of inflammatory and autoimmune conditions. Becoming sick usually involves a genetically-susceptible host exposed to indoor air pollution.
This process disrupts the immune system and may propagate chronic inflammation. This chronic inflammation is measurable in the blood with markers such as complement C4a, transforming growth factor beta-1, and matrix metalloproteinase-9. Moreoever, the inflammation will almost universally damage the hormonal system known as the hypothalamic-pituitary-adrenal axis. This endocrine disruption may alter hormone levels such as anti-diuretic hormone and testosterone.
This immune and endocrine damage can, in turn, causes symptoms in every organ system in the body. In addition to fatigue and brain fog, devastating symptoms may involve food sensitivity, bodily pain, and multiple chemical sensitivity—a condition in which exposures to low levels of environmental chemicals and scents, such as cleaning solvents, precipitate an acute decline. The range and severity of symptoms determine whether there is a mild impairment or long-term disability.
How Indoor Air Pollution Causes Chronic Inflammatory Response Syndrome
Damp buildings have increased levels of biological contaminants.
The dampness on building materials initiates a period of frenzied growth as the moisture-activated mold and bacteria digest building materials. Within forty-hours of water-damage, this microbial growth will take place. According to an in vitro study, wet paper and wood building materials, such as gypsum, become over two hundred times more toxic. These microbes, along with their metabolic agents, are emitted into the air.
The human immune system is designed to detect foreign substances. The microbes contains inflammatory triggers called pathogen-associated molecular patterns and damage-associated molecular patterns. These inflammatory triggers are found on cell walls of mold and bacteria, in addition to sugar, protein, and fat particles made by these microbes. Each breath in a water-damaged building is a stressor to the immune system as the immune tissue in lungs detects these inflammatory and toxic irritants.
Due to their small size, some of the particles can penetrate beyond the lungs directly into the brain, where they trigger neuroinflammation, and into the blood stream, where they cause systemic inflammation. The circulation brings the harmful particles and cytokines to every part of the body that has a blood supply. It is therefore through circulation that systemic inflammation can damage any organ system.
A key aspect of inflammatory cascades is, once initiated, they can become self-perpetuating—even with the cessation of mold exposure. Consider how an immune condition such as rheumatoid arthritis or multiple sclerosis can progress relentlessly, once the immune system crosses an invisible tipping point.