Among patients diagnosed with an invasive mold infection at four Atlanta hospitals over five years, 45 percent were dead within 90 days.
That figure, published by the CDC in a Surveillance Summaries report, covers 449 confirmed cases identified between 2020 and 2024. Half of those patients required intubation and mechanical ventilation. Forty-three percent had been in an intensive care unit in the two weeks before the specimen that identified their infection was collected.
Before saying anything else, one point needs to be clear, because the word "mold" invites a specific and wrong conclusion. This report is not about mold in houses, basements or air vents. Invasive mold disease is what happens when mold spores that healthy people inhale harmlessly every day take hold in someone whose immune system cannot clear them. The patients in this report were transplant recipients, cancer patients, people on immune-suppressing drugs, and people who were critically ill. Readers who are none of those things are not the population described here.
Why Nobody Knew These Numbers
Invasive mold disease is not a nationally notifiable condition. No state is required to report it, and no national count exists.
That gap is the reason this report was written. CDC runs active, laboratory-based surveillance through the Georgia Emerging Infections Program at three laboratories serving four Atlanta hospitals: two academic hospitals with their outpatient clinics, one federal hospital and one community hospital. Investigators reviewed laboratory records for positive mold cultures and positive Aspergillus galactomannan tests, then went through medical charts to sort real infections from contamination and colonization.
That sorting is the hard part. Of 968 patients flagged as potential cases, only 449, or 46 percent, turned out to have invasive mold disease. Mold growing in a culture can mean infection, or it can mean the organism was simply present on a surface or in an airway without causing disease, or it can mean the sample was contaminated in the laboratory. Symptoms are nonspecific. Confirming a diagnosis often requires biopsy, which is risky in patients who are already critically ill.
The resulting incidence figures are the first of their kind for this system. At the two academic hospitals, the pooled average annual rate was 4.8 inpatient cases per 100 inpatient beds and 14.0 ICU cases per 100 ICU beds. At the community hospital, the rates were 2.8 and 10.2. CDC frames these as benchmark numbers that hospitals can use to tell an ordinary run of sporadic cases apart from an outbreak, noting that given how rare and how severe these infections are, even small increases should prompt a look for a common source.
What the Infections Looked Like
Aspergillus species accounted for 71 percent of cases, with Aspergillus fumigatus the single most common at 21 percent. Fusarium species followed at 4 percent, then Mucorales at 4 percent and Scedosporium at 3 percent.
Infections were most often pulmonary, at 68 percent. Cutaneous or deep tissue infections accounted for 11 percent, sinus or nasal infections 10 percent, and central nervous system infections 9 percent.
Patients skewed older and male. Forty-three percent were aged 45 to 64 and 39 percent were 65 or older. Sixty-five percent were male. Patients aged 18 and under accounted for less than 1 percent, though the surveillance system does not include a children's hospital, which limits what the data can say about pediatric cases.
Most patients were treated. Eighty-one percent received an antifungal effective against molds, most often isavuconazole, followed by voriconazole and amphotericin B. The high mortality occurred despite that treatment rate, which is part of why the report's authors conclude that new antifungal agents and better treatment protocols are needed.
Patients who also had a current or recent COVID-19 diagnosis fared substantially worse. Among that group, 66 percent had been in an ICU in the preceding two weeks, compared with 39 percent of other patients, and 90-day mortality was 66 percent compared with 41 percent.
The Finding Clinicians Should Notice Most
The most consequential number in the report is not the mortality rate. It is that 35 percent of patients with invasive mold disease had none of the classic host risk factors that clinicians are trained to look for.
Those established risk factors include prolonged neutropenia, hematologic malignancy, stem cell or solid organ transplant, extended high-dose corticosteroid use and severe autoimmune disease. More than a third of confirmed cases had none of them. Surveillance or diagnostic approaches that screen only for the textbook patient would have missed those cases entirely.
The report also flags conditions that were more common among infected patients but are not on the classic list, including end-stage renal disease, cirrhosis and severe burns within the previous 90 days. Concurrent critical illness, particularly severe COVID-19 and severe influenza, is increasingly recognized as a risk factor in its own right.
For patients and families, the practical translation is narrow and specific. If someone is immunocompromised or critically ill and develops a persistent fever, worsening breathing, sinus pain with facial swelling, or new confusion that is not explained, invasive fungal disease is a reasonable thing to ask the treating team about. It is not something to self-diagnose, and no over-the-counter product treats it. Nobody should stop or change an immunosuppressive medication over this. Those drugs prevent organ rejection or control disease, and stopping them creates a far more immediate danger than a rare infection.
What This Report Cannot Tell You
The limitations matter as much as the findings, and CDC states them plainly.
The data come from four facilities in one metropolitan area, which limits how far the findings generalize. These are not national incidence rates and should not be reported as such. The system may miss cases because mold detection techniques have limited sensitivity, and it did not use DNA-based methods such as PCR or metagenomic sequencing during the study period, though those were added starting with 2025 data. Patients with cystic fibrosis were excluded because mold colonization is so common in that group. No children's hospital participates. The analysis counted only each patient's first infection.
One further caution about the mortality figure: 45 percent is 90-day all-cause mortality, not deaths caused by the mold infection. These were severely ill people, many with advanced cancer or organ failure. The number describes how sick this population is, not how lethal the fungus is on its own.
For broader context, the report cites prior analyses estimating that invasive mold diseases are associated with more than 15,000 US hospitalizations and over $1.3 billion in direct medical costs annually.
CDC says continued surveillance could help identify emerging at-risk populations, support earlier recognition and treatment, and detect health care-associated outbreaks. The system has already expanded its detection methods for 2025 data. MedicalDaily will report subsequent surveillance updates and any move toward making invasive mold disease reportable.
Frequently Asked Questions
Is this about mold in my house? No. This report concerns invasive infections in people with weakened immune systems or critical illness. Healthy people inhale mold spores routinely without developing invasive disease.
Who is actually at risk? Transplant recipients, people with blood cancers, patients on immune-suppressing medications, people with prolonged neutropenia, and critically ill patients, particularly those with severe COVID-19 or influenza.
Does 45 percent mean the fungus killed half of them? No. That is 90-day all-cause mortality in a severely ill population. It reflects how sick these patients were overall, not the lethality of the infection alone.
Are these national numbers? No. The surveillance covers four hospitals in metropolitan Atlanta. Invasive mold disease is not nationally notifiable, and no national incidence estimate exists.
What was the most common organism? Aspergillus species accounted for 71 percent of cases, with Aspergillus fumigatus most common. Infections were most often pulmonary, at 68 percent.
What is the most important finding for doctors? That 35 percent of confirmed cases occurred in patients without the classic host risk factors, meaning screening based only on textbook risk profiles would miss more than a third of cases.
Should an immunocompromised patient change medications? No. Immunosuppressive drugs prevent organ rejection and control serious disease. Any concern should be raised with the treating clinician rather than acted on independently.
