A major new research initiative is investigating whether exposure to toxic mold compounds may trigger or worsen myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a debilitating illness affecting up to 3.3 million Americans. Nova Southeastern University (NSU) researchers have been awarded a $3 million grant from the National Institutes of Health (NIH) to study the potential connection between mycotoxins (harmful compounds produced by mold) and immune dysfunction in ME/CFS patients.

Why Is This Research Important for ME/CFS Patients?

ME/CFS remains one of medicine's most puzzling conditions. According to the U.S. Centers for Disease Control and Prevention, between 836,000 and 3.3 million Americans live with ME/CFS, yet an estimated 90 percent remain undiagnosed. The disease has no diagnostic test and few effective treatment options, leaving patients struggling with extreme fatigue, brain fog, cognitive impairment, sleep disturbances, and post-exertion malaise that can worsen after minimal physical activity.

What makes this research groundbreaking is that previous patient surveys have shown some ME/CFS patients report symptom onset following exposure to mold-contaminated environments. Until now, this connection has been largely overlooked by mainstream medicine, despite affecting millions of people.

"ME/CFS is a systemic disease. It affects many parts of the body, including the gut and the brain. For many patients, symptoms begin after exposure to viruses or other environmental factors, but we still don't fully understand what causes the disease to start," said Lubov Nathanson, Ph.D., associate professor at the Dr. Kiran C. Patel College of Osteopathic Medicine and principal investigator of the study.

Lubov Nathanson, Ph.D., Associate Professor and Principal Investigator, Nova Southeastern University

What Will the Research Actually Study?

The five-year project, funded through April 2031, will examine how environmental exposure to mycotoxins may contribute to immune dysfunction in ME/CFS patients. Researchers will collect biological samples from over 200 study participants and measure their exposure to mycotoxins using advanced techniques. They will then evaluate whether specific environmental exposures are associated with biological changes linked to ME/CFS.

The goal is to identify biomarkers (measurable biological indicators) that could lead to earlier diagnosis, more personalized treatment approaches, and new insights into factors that may contribute to disease development. This represents a significant shift in how the medical community approaches ME/CFS, moving from dismissing environmental factors to investigating them rigorously.

"For decades, patients with ME/CFS have faced delayed diagnoses, limited treatment options, and significant uncertainty about the causes of their illness. Understanding how environmental factors influence disease development could help identify biomarkers, improve diagnosis, and ultimately lead to more targeted treatments," said Nancy G. Klimas, M.D., co-investigator and director of NSU's Institute for Neuro-Immune Medicine.

Nancy G. Klimas, M.D., Co-Investigator and Director, Institute for Neuro-Immune Medicine

How Does Mold Exposure Affect the Body?

Mold is far more complex than most people realize. When mold grows in damp, water-damaged buildings, it releases multiple types of harmful compounds simultaneously. Understanding these pathways is crucial to understanding why mold exposure can trigger such varied and severe symptoms.

• Mold Spores: Tiny reproductive particles that float through the air and are easily inhaled into the lungs, triggering respiratory symptoms in susceptible individuals.
• Mold Fragments and Dust: Fragments of mold cells and spores accumulate in household dust at much higher levels than spores alone, potentially responsible for 70 to 90 percent of inhalation exposure according to toxicology research.
• Mycotoxins: Noxious compounds produced by mold that are even smaller than spores and have been linked to dangerous symptoms ranging from respiratory issues to neurological effects and systemic illness.
• Microbial Volatile Organic Compounds (mVOCs): Gases emitted by mold responsible for the musty, mildew smell that can negatively impact health and trigger symptoms in people with chemical sensitivities.

The challenge for researchers is staggering: there are hundreds of indoor fungi species, and a single species can produce more than 90 different mycotoxins, mVOCs, and other compounds. That means tens of thousands of different compounds could potentially cause health problems, yet we have limited research identifying which ones cause which symptoms.

What Does the "Multiple-Hit Hypothesis" Mean for Mold and ME/CFS?

Scientists are increasingly exploring whether mold exposure fits into what's called the "multiple-hit hypothesis." This theory suggests that compounded viral, bacterial, and environmental exposures could destabilize the body's equilibrium and increase the risk of developing chronic illnesses like ME/CFS and Long COVID. In other words, mold exposure might not be the sole cause of these diseases, but rather one environmental factor that, combined with other stressors like viral infections, could trigger illness in susceptible people.

This framework helps explain why some people develop ME/CFS after a viral infection, while others develop it after mold exposure, and still others may have multiple contributing factors. It also explains why some patients report their symptoms worsening dramatically after moving into mold-contaminated spaces, even if they had been managing their illness relatively well beforehand.

How Will Climate Change Increase Mold Risk?

The timing of this research is critical because mold contamination rates are expected to increase in the coming years. Flooding from severe weather events linked to climate change will increase the risk of water damage and mold growth in buildings. Nearly half of buildings in the U.S. already have mold or dampness, and this proportion is likely to rise as extreme precipitation events become more frequent and intense.

This creates a particular concern for people with disabilities and chronic illnesses. Those with ME/CFS, Long COVID, and related conditions are at particularly high risk from mold exposure because they often lack the resources to move to a different space or pay for professional mold remediation. For people already managing severe illness, being trapped in a mold-contaminated home could be catastrophic.

Steps to Reduce Your Mold Exposure Risk

• Monitor Humidity Levels: Keep indoor humidity below 50 percent to prevent mold growth, as mold thrives in damp environments. Use a hygrometer to track moisture levels in your home.
• Address Water Damage Immediately: If you experience flooding, leaks, or water damage, dry affected areas within 24 to 48 hours and address the source of moisture to prevent mold colonization.
• Improve Ventilation: Ensure bathrooms and kitchens have proper exhaust fans vented to the outside, and open windows when weather permits to reduce indoor moisture and improve air circulation.
• Inspect Hidden Areas: Regularly check basements, crawl spaces, attics, and areas around windows and pipes for signs of water damage or mold growth, as mold often develops in spaces people don't regularly see.
• Use HEPA Filtration: Consider air filtration systems with HEPA filters to capture mold spores and fragments, particularly if you live in a humid climate or have experienced water damage.

For people with ME/CFS or suspected mold sensitivity, being proactive about mold prevention is especially important, as research increasingly suggests that mold exposure can trigger or significantly worsen symptoms in this population.

What Comes Next for ME/CFS Patients?

The NSU research project represents a major step forward in legitimizing environmental factors as potential contributors to ME/CFS. By identifying biomarkers linked to mold exposure and immune dysfunction, researchers hope to develop diagnostic tools that could help the millions of undiagnosed patients finally get answers. The study will also provide evidence that could inform treatment protocols and help patients understand whether their symptoms may be connected to mold exposure in their living spaces.

Until now, mold exposure has been a largely understudied and little-understood phenomenon in the context of chronic illness, with limited and largely untested treatments available. This research could change that, offering hope to patients who have struggled for years without answers or effective medical support.