Temporal surveillance of Coccidioides in Aerosols in Mesa, Arizona

Valley fever is a lung infection caused by the inhalation of infectious spores from the fungus Coccidioides spp. Coccidioides is a genus of soil dwelling fungi endemic to the arid regions of the southwestern United States, Mexico, and Central and South America. Few Valley fever studies have focused on detecting Coccidioides spores in airborne respirable particles, which is the primary infection vector. This study looks at the presence of Coccidioides in air at a highly soil positive site in Mesa, Arizona. Aerosol samples were collected for 24 h every 6 days, following the Environmental Protection Agency sampling schedule. Meteorological data were collected from a nearby weather station. Coccidioides were detected in ∼68% of the aerosol samples. Bulk PM₁₀did not have a statistically significant relationship with presence of Coccidioides; however, there was a significant relationship between the amount of crustal material in the aerosols and presence of Coccidioides. Previous studies link the presence of Coccidioides in air with bulk PM₁₀concentrations; however, we found that bulk PM₁₀concentrations give an incomplete story. Additionally, there were statistically significant relationships with the presence of Coccidioides and meteorological parameters, including relative humidity, temperature, and wind speed. This study emphasizes the importance of dust entrainment in the transmission of Coccidioides.