New York: A first-of-its-kind US study suggests invasive mould infections may be an underappreciated and potentially deadly public health threat.
Researchers detected around 450 cases in hospitals in the Atlanta area over five years, with about one-third of the patients dying during hospitalisation.
The findings, published this week by the US Centers for Disease Control and Prevention (CDC), stem from an effort to better estimate how common these illnesses are. The US government does not require doctors to report such infections.
"It's kind of the first time we've had an estimate like this," said Dr Jeremy Gold, the study's senior author.
Gold said it is important to understand the scale of the problem now because it could become more significant in the future. Researchers have found that mould exposure is a recurring issue following hurricanes, floods and other natural disasters linked to 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.
Gold also noted that a growing population of older adults, who are more vulnerable to such illnesses, could contribute to an increase in cases.
Invasive mould diseases are rare infections caused by certain mould species. Most people become infected by inhaling mould spores, although the spores can also enter the body through cuts, wounds or contaminated medical equipment.
The spores do not cause health problems for most people, but they can be life-threatening for vulnerable groups, including older adults, cancer patients and others with weakened immune systems.
Previously, CDC researchers estimated that more than 15,000 hospitalisations each year could be associated with invasive mould disease.
To better understand the local burden of disease, the research team worked with four hospitals in the Atlanta area and their affiliated outpatient clinics to identify potential cases between 2020 and 2024.
Researchers initially identified nearly 1,000 potential cases but narrowed the number to around 450 after excluding patients who showed signs of exposure but did not meet the criteria for invasive mould disease.
The study found that hospitals can expect to see three to five cases annually for every 100 inpatient beds. Rates were higher at larger academic hospitals, which typically treat more complex medical conditions.
Most patients had weakened immune systems or, in several cases, experienced immune suppression after contracting COVID-19.
Gold said mould exposure can occur in hospitals or other healthcare settings, but the study did not attempt to determine where each patient was first exposed.
He added that while the findings cannot be directly applied to other parts of the United States, where mould exposure may vary, they provide hospital administrators with a useful benchmark to determine whether the number of cases they observe reflects expected levels or signals a possible outbreak.
Jenks described the findings as "valuable" but said that similar studies conducted in other regions of the United States would help provide a more comprehensive understanding of the issue.
