*Purpose: In recent decades, climate change and other factors have led to a global increase in wildfires. After a large fire in Northern California in 2017, we anecdotally noted more invasive fungal infections (IFI) at our quarterary care hospital that led us to hypothesize a link between the two. We sought to determine whether exposure to wildfires was associated with an increased risk of IFI.

*Methods: We performed time series analysis of admissions for infections with invasive mold (all molds, including Aspergillus), Aspergillus spp, and Coccidioides spp during periods with and without fire across twenty-two hospitals in California between October 2014 and May 2018. All hospitals were members of Vizient, Inc and consistently reported into the Clinical Database Resource Manager. Accounting for clustering by hospital and controlling for season, we used quasi-Poisson regression to determine whether there was an increased risk of IFI in months where there was a large fire (> 5000 acres) within a 200-mile radius of the hospital. Invasive Candida infections served as controls as these tend to be endogenous and not typically associated with environmental exposures.

*Results: During the study period, there were a total of 968 months of time across all the hospitals with 400 months (41.3%) experiencing large fires. Average rates of invasive mold, aspergillosis, coccidioidomycosis, and invasive candidal infections were 5.84, 2.89, 0.88, and 1.01 cases per 1000 admissions, respectively. Table 1 shows incidence rate ratios for IFI during wildfire exposure.

*Conclusions: Months during which large wildfires occurred within 200 miles of a hospital were associated with an increased risk of invasive mold infection, aspergillosis, and coccidioidomycosis but not with candidal infection. Wildfire smoke contains particulate matter, which in turn contains fungal spores. One possible mechanism for the increased risk is that wildfire smoke leads to spread of fungal spores that can be inhaled by at-risk individuals. It is possible that the association between fires and IFI may result from environmental circumstances that predispose to fire rather than to the actual fires; further work needs to be done to incorporate these conditions into the model to elucidate our observation. If borne out in further prospective studies, the association between IFI and wildfire exposure has important implications for prophylaxis and monitoring of at-risk patients.

Disclaimer: This abstract does not necessarily reflect USEPA policy.

« Back to 2019 American Transplant Congress