A novel U.S. study indicates that invasive mold infections may represent an underappreciated and potentially fatal threat, with researchers identifying approximately 450 cases in Atlanta-area hospitals over a five-year period. About one-third of these patients died during their hospitalization, according to findings published by the U.S. Centers for Disease Control and Prevention (CDC).
The study represents an effort to better quantify the prevalence of these illnesses, which are not federally mandated for reporting by physicians. "It's kind of the first time we've had an estimate like this," said Dr. Jeremy Gold, the study's senior author and a researcher with the CDC.
Researchers suggest the problem could escalate in the future, noting that mold exposure is a recurring issue following natural disasters such as hurricanes and floods, which are influenced by climate change. Dr. Jeffrey Jenks, an infectious disease researcher at Duke University, agreed that the frequency of fungal infections is likely to increase with climate change. Furthermore, an expanding elderly population is becoming more susceptible to such infections.
Invasive mold diseases stem from infections caused by specific species of mold. Most individuals contract these infections by inhaling mold spores, though entry into the body can also occur through wounds or contaminated medical equipment. While mold spores do not typically cause health problems for the general population, they can be life-threatening for vulnerable groups, including the elderly, cancer patients, and individuals with compromised immune systems.
Previous CDC estimates suggested that over 15,000 hospitalizations annually might be linked to invasive mold disease. To assess local prevalence, the research team collaborated with four Atlanta-area hospitals and their affiliated outpatient clinics, examining potential cases between 2020 and 2024. Initially, nearly 1,000 potential cases were identified, but this number was narrowed to around 450 after excluding patients who showed signs of exposure but did not meet the criteria for invasive mold disease.
The study found that hospitals could expect to encounter three to five cases per year for every 100 inpatient beds, with higher rates observed at larger academic hospitals that typically manage more complex illnesses. A significant portion of the identified patients had impaired immune systems or had experienced weakened health after contracting COVID-19.
While mold exposure can occur within healthcare facilities, the study did not pinpoint the initial source of exposure for each patient. Gold noted that generalizing the Atlanta findings to other regions with differing mold prevalence is challenging. However, he suggested the data could provide hospital administrators with a benchmark to assess whether their case numbers align with expectations or indicate an outbreak. Jenks characterized the study's findings as "valuable" but expressed a need for similar studies in other parts of the United States to provide broader insights.