Detection of airborne Coccidioides spores using drones in the Carrizo Plain, California: A pilot study
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Background and Objectives: Coccidioidomycosis is an emerging fungal infection caused by inhalation of airborne spores of the Coccidioides genus. While Coccidioides immitis has been detected in soils across California, few studies have detected the spores in air, limiting understanding of the environmental factors that give rise to their dispersal. Here, we examine a novel sampling strategy – air filtration with unmanned aircraft systems (UAS) – as a means of detecting C. immitis in aerosolized soil dust.
Approach: We conducted a pilot study in September 2023 at 14 locations across the Carrizo Plain National Monument, an area with confirmed C. immitis soil presence. We carried out 41 20-minute flights using two UAS equipped with an 8 L/min aerosol sampler and Purple Air particulate matter (PM) Monitor. At each site, we sampled air under ambient conditions using a single flight at 10-20 m altitude and under a simulated high-wind event using paired flights at <5 m altitude (to mobilize dust) and 10-20 m altitude. We concurrently collected soils (n=168) using an interrupted radial transect design. We will assess prevalence of C. immitis on filters and soils using qPCR and use logistic regression to identify associations with flight altitude, PM, wind speed, temperature, and humidity.
Results and Conclusions: Our findings will inform a larger-scale sampling campaign over the coming year aimed at understanding the aerosolization of C. immitis and potential transport in dust-generating events, like high winds and wildfires. Our results will inform efforts to control and prevent coccidioidomycosis in endemic regions.