What a New CDC Study Reveals About Invasive Mold Disease
Rare, serious mold infections deserve attention—but they should not be confused with ordinary household mold exposure.
Written by Paul Sterling
Mold is often discussed in connection with musty odors, water damage, allergy symptoms, asthma, and indoor air quality. A newly released report from the Centers for Disease Control and Prevention examines a very different and far more serious category of illness: invasive mold disease.
Invasive mold disease occurs when certain molds infect and invade tissue or organs. These infections are rare and primarily affect people who are hospitalized, immunocompromised, receiving cancer treatment, taking immunosuppressive medication, or living with other serious medical conditions.
The CDC study reviewed five years of active surveillance data from four hospitals and associated outpatient clinics in metropolitan Atlanta. Its findings provide one of the clearest recent pictures of how invasive mold infections are identified, who is affected, and how severe the outcomes can be.
Just as important, the study does not show that ordinary household mold exposure commonly causes invasive infections. It studied a highly selected hospital population, not the general public, and it did not investigate where individual patients encountered mold.
What Is Invasive Mold Disease?
Most people encounter mold spores every day without developing an invasive infection. Our immune systems are generally able to clear or contain the spores we inhale.
Invasive mold disease is different. It can occur when mold enters and damages body tissue, most commonly in the lungs but also in the sinuses, skin, central nervous system, and other areas. The molds most often associated with these infections include Aspergillus, Mucorales, Fusarium, and Scedosporium species.
These infections can be difficult to diagnose. Symptoms may be nonspecific, and a positive clinical mold culture does not automatically prove that a patient has an invasive infection. Mold detected in a specimen could represent true disease, colonization, or contamination. Physicians must consider laboratory findings together with imaging, symptoms, medical history, risk factors, and response to treatment.
What the CDC Study Examined
The CDC and the Georgia Emerging Infections Program conducted active, laboratory-based surveillance at three laboratories serving four Atlanta hospitals from 2020 through 2024.
Researchers reviewed 968 patients whose laboratory results suggested a potential invasive mold infection. Cases were then evaluated using established clinical, laboratory, radiologic, and host-risk criteria. Patients could be classified as proven, probable, or surveillance cases.
Of the 968 potential cases reviewed, 449 patients—46 percent—were classified as having invasive mold disease.
That gap between a positive mold-related laboratory result and a confirmed or clinically treated infection is important. Test results are meaningful only when they are interpreted in the proper context. Clinical testing and environmental mold testing answer different questions, but both require more than a single isolated number or laboratory finding.
Key Findings From the Report
Aspergillus Was the Most Common Mold Identified
Aspergillus species were associated with 319 of the 449 invasive mold disease cases, representing 71 percent of all cases. Aspergillus fumigatus was the most frequently identified individual species.
Other molds included Fusarium, Mucorales, and Scedosporium, but each accounted for a much smaller percentage of cases.
The Lungs Were the Most Common Site of Infection
Pulmonary infections represented 68 percent of cases. Sinus or nasal infections, skin and deep-tissue infections, and central nervous system infections occurred less frequently.
This pattern is not surprising because inhalation is a common route through which airborne mold spores enter the body. Again, inhaling mold spores does not mean a person will develop an invasive infection. The overwhelming majority of people do not.
Outcomes Were Often Severe
Among patients classified as having invasive mold disease:
- 43 percent had been admitted to an intensive care unit during the two weeks before the mold specimen was collected.
- 50 percent required intubation and mechanical ventilation.
- The 90-day all-cause mortality rate was 45 percent among the cases for which complete mortality data were available.
“All-cause mortality” means the study counted deaths from any cause within 90 days. It does not mean mold was necessarily the sole cause of every death. Many patients had complex and serious underlying illnesses.
Most Patients Had Recognized Risk Factors—but Not All
Sixty-five percent of patients had at least one classic host factor used in invasive fungal disease definitions. Common risk factors included hematologic cancers, prolonged neutropenia, organ transplantation, and immunosuppressive treatment.
The study also found that 35 percent of cases did not have one of the classic host factors included in the research definition. That does not mean these patients were otherwise healthy. Some had serious conditions or treatments that were not captured by the traditional criteria. The finding does suggest that clinicians and surveillance systems should not rely too narrowly on a standard risk-factor checklist.
Patients With Recent COVID-19 Had Worse Outcomes
Fifty-eight patients with invasive mold disease had a current or recent COVID-19 diagnosis. This subgroup experienced higher rates of ICU admission and higher 90-day all-cause mortality than patients without recent COVID-19.
The report does not establish that COVID-19 alone caused the mold infections. Severe viral illness, lung damage, intensive care treatment, corticosteroid use, and other medical factors can overlap and contribute to risk.
What This Study Does—and Does Not—Mean for Homeowners
The study confirms that invasive mold disease is a serious medical problem. It does not establish that people living in homes with mold are likely to develop invasive infections.
The surveillance population came from four hospitals and included many people with severe illnesses, immune suppression, transplants, cancer, prolonged corticosteroid use, or other major medical risk factors. The results cannot be used to estimate the invasive mold infection risk for the general population.
The study also did not inspect patients’ homes or determine where their exposure occurred. Mold is common outdoors and indoors, and exposure can happen in many settings.
For most people, indoor mold concerns are more likely to involve allergy symptoms, asthma aggravation, irritation, odors, property damage, or other noninvasive health effects. Those issues still deserve attention, but they should not be conflated with invasive fungal disease.
Why the Findings Still Matter for Indoor Environments
Although the report was clinical rather than building-focused, it reinforces several practical principles.
Moisture Control Remains the First Line of Prevention
Mold needs moisture to grow. Roof leaks, plumbing failures, flooding, condensation, damp crawl spaces, and poorly managed construction materials can create conditions that support fungal growth.
Promptly identifying and correcting moisture sources reduces the opportunity for mold amplification. Water-damaged materials should be evaluated and dried or removed appropriately rather than simply covered or painted.
High-Risk Individuals Need Medical Guidance
People who have received a transplant, are undergoing cancer treatment, take significant immunosuppressive medication, or have another serious immune-compromising condition should ask their medical team about mold and construction-dust precautions.
A physician can provide guidance tailored to the patient’s diagnosis and treatment. A mold inspector cannot determine whether a building caused an illness or diagnose an invasive infection.
Disturbing Contaminated Materials Can Increase Airborne Particles
Demolition, renovation, and improper do-it-yourself removal can release mold spores and fragments into the air. Containment, dust control, filtration, and appropriate remediation practices are especially important when a medically vulnerable person occupies the building.
Evidence Should Drive Decisions
A visible stain, a musty odor, a laboratory result, or a health symptom should not be interpreted in isolation. A sound environmental assessment considers the building history, moisture conditions, visual findings, material conditions, sampling strategy, and laboratory data together.
This is particularly important for medically sensitive clients, who can be harmed both by an overlooked moisture problem and by unnecessary, overly broad remediation based on weak evidence.
How Mold Inspection Sciences Can Help
Mold Inspection Sciences provides independent mold inspection and testing. Because we do not perform remediation, our findings and recommendations are not tied to selling cleanup or construction work.
A professional assessment may include:
- A detailed review of the property’s moisture and water-intrusion history
- Visual inspection of accessible areas
- Moisture measurements and infrared imaging where appropriate
- Targeted air, surface, dust, or material sampling based on observed conditions
- Laboratory analysis and a written report explaining the findings
- Recommendations for next steps and, when needed, post-remediation verification
Environmental testing cannot diagnose a medical condition, and no environmental test can prove by itself that a building caused a specific infection. For clients working with a physician, however, a careful inspection can provide useful information about whether mold growth, water damage, or other environmental concerns are present.
To schedule an independent mold inspection or testing consultation, call Mold Inspection Sciences at 1.800.619.6653.
The Bottom Line
The new CDC report provides valuable baseline data on a rare but dangerous category of fungal infection. In the Atlanta hospital surveillance system, invasive mold disease was most often pulmonary, most frequently associated with Aspergillus, and linked with high rates of intensive care, mechanical ventilation, and mortality.
The correct takeaway is not that everyday mold exposure routinely leads to invasive disease. It is that mold-related health questions require precision. The type of illness, the patient’s medical risk, the building conditions, and the testing evidence all matter.
For property owners, the practical response remains straightforward: control moisture, investigate suspected mold carefully, avoid disturbing contaminated materials without proper precautions, and rely on qualified medical and environmental professionals for the questions each is trained to answer.
Source
Sajewski ET, Mackey C, Thomas S, et al. “Active Surveillance for Invasive Mold Disease — Four Hospitals, Atlanta, Georgia, 2020–2024.” MMWR Surveillance Summaries. July 30, 2026;75(No. 5).
About the author
Paul Sterling
Paul Sterling is the Chief Technology Officer at Mold Inspection Sciences, where he combines his passions for technology, creativity, and education to help people better understand their indoor environments. Co-creator of Moldware and a multiple-time Umbraco MVP, Paul brings decades of software development experience to his work. He also plays a leading role in MIS's marketing and educational initiatives, with a particular interest in making complex environmental topics accessible through engaging content, creative storytelling, and innovative digital experiences.
Paul has spoken at Codegarden and the Umbraco U.S. Summit and was an Umbraco Certified Trainer from 2009 through 2017. Explore his speaking and teaching experience.
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