NEW YORK – Invasive mold infections may pose a more serious and overlooked public health risk in the United States than previously understood, according to a first-of-its-kind study.
Researchers identified roughly 450 cases in hospitals across the Atlanta area during a five-year period. About one in three patients died while hospitalized, underscoring the potential severity of these infections.
The findings, released this week by the U.S. Centers for Disease Control and Prevention, are part of an effort to measure how often these illnesses occur. Currently, doctors are not required to report invasive mold infections to public health authorities.
“It’s kind of the first time we’ve had an estimate like this,” said Dr. Jeremy Gold of the CDC, the study’s senior author.
Gold said understanding the scope of the problem is increasingly urgent because the threat could expand. Researchers have linked mold exposure to the aftermath of hurricanes, floods and other natural disasters, events that are being intensified or influenced by climate change.
“I agree that the frequency of fungal infections will likely increase with climate change,” said Dr. Jeffrey Jenks, an infectious disease researcher at Duke University.
At the same time, Gold noted, the nation’s aging population may add to the concern, since older adults can be more vulnerable to these kinds of infections.
Invasive mold diseases are uncommon infections caused by specific mold species. Most patients become infected after breathing in mold spores, though the organisms can also enter through cuts, wounds or contaminated medical equipment.
The spores don’t cause health problems for most people, but they can be life-threatening to some, including the elderly, cancer patients and others with weakened immune systems.
Previously, CDC researchers estimated more than 15,000 hospitalizations a year could be tied to invasive mold disease.
To better understand how common cases might be at a local level, the research team worked with four Atlanta-area hospitals and their affiliated outpatient clinics to look for potential cases from 2020 to 2024.
They initially identified nearly 1,000 potential cases, but winnowed the number down to about 450 by ruling out patients who may have had signs of exposure but didn’t qualify as having invasive mold disease.
The researchers found that hospitals can expect to see 3 to 5 cases per year for every 100 inpatient beds. The rates were higher at larger academic hospitals that tend to see more complicated illnesses.
Most patients had impaired immune systems or — in a number of cases — were weakened after falling sick from COVID-19.
Mold exposures can occur in hospitals or other healthcare facilities, but the study did not try to determine where each patient was first exposed, Gold said.
It’s hard to generalize what was seen in the Atlanta area to other parts of the country where mold may be more or less of a problem, he said. But it should give hospital administrators at least a rough idea about whether the number of cases they see is what might be expected or whether it’s an outbreak, Gold added.
Jenks called the study’s findings “valuable,” but said “seeing results from similar studies done in different parts of the United States would be helpful.”
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