Monitoring fungal spores in the outdoor air can predict surges in flu and COVID-19 infections, especially during the fall, according to a new study. The study is presented at ASM Microbe 2025 in Los Angeles, the annual meeting of the American Society for Microbiology.
"By monitoring the air we breathe, we may be able to better forecast and prepare for seasonal outbreaks of respiratory viral infections," said presenting study author Félix E. Rivera-Mariani, Ph.D., associate professor of Biochemistry and Special Topics in Biology at Lynn University in Boca Raton, Fla., and founder and principal investigator at the RIPLRT Institute, in Fort Lauderdale, Fla.
The researchers wanted to understand the short-term role of environmental exposures-specifically fungal spores and pollen-in triggering or amplifying the incidence of respiratory viral infections such as COVID-19 and influenza. The ecology of Puerto Rico offers a unique natural laboratory due to its consistent and endemic year-round presence of airborne fungi and pollen. Despite the known links between these exposures and asthma or allergies, their role in viral infection trends hasn't been thoroughly studied.
In the new study, the researchers examined daily data, from 2022 to 2024, in 2 major health regions in Puerto Rico-San Juan and Caguas. The data included the daily incidence of people diagnosed with COVID-19 and flu, and the concentrations of airborne fungal spores and pollen recorded on the same days. The scientists then implemented statistical and machine learning models to see if high levels of these environmental exposures could predict spikes in flu and COVID-19 cases within the same week or the following week (called lag-effect).
They discovered that airborne concentrations of fungal spores- but not pollen-were strongly linked to increases in flu and COVID-19 cases. When airborne concentrations of fungal spores rose, the scientists often saw a jump in infections within a few days. The models were able to predict flu and COVID-19 surges with high accuracy, particularly in the fall season, in both San Juan and Caguas. Pollen didn't show the same connection nor prediction.
The findings from our study suggest that monitoring airborne fungal spore levels could help predict short-term outbreaks (spikes) of flu and COVID-19, giving public health systems an early warning signal. Our findings also highlight the potential role of environmental factors-not just person-to-person spread-in contributing to the incidence of respiratory viral infections. That could open new doors for targeted public health alerts, especially in areas with high outdoor airborne fungi."
Félix E. Rivera-Mariani, Ph.D., associate professor of Biochemistry and Special Topics in Biology, Lynn University
The study's investigators say that Puerto Rico was an ideal setting for the study, not only because of its high environmental exposure levels, but also because it has active fungal and pollen monitoring stations in downtown Caguas and in San Juan on the University of Puerto Rico, Medical Sciences Campus. "These findings may help inform environmental risk alerts, particularly for vulnerable populations like the elderly or those with asthma and allergic rhinitis," Rivera-Mariani said.
To follow up on the new findings, Rivera-Mariani and colleagues would like to investigate whether these environmental exposures also correlate with severe outcomes like hospitalizations or deaths, and whether similar patterns exist in other regions beyond Puerto Rico. "We also hope to collaborate with local health agencies to explore incorporating fungal surveillance into existing outbreak forecasting systems," Rivera-Mariani said.
Genomic analysis reveals how bird flu jumped from wild birds to poultry and people