Award Date

5-1-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Environmental and Occupational Health

First Committee Member

Patricia Cruz

Second Committee Member

Mark P. Buttner

Third Committee Member

Steven Medley

Fourth Committee Member

Karl Kingsley

Number of Pages

139

Abstract

Fungal exposure can cause acute and chronic illnesses or exacerbate existing illnesses. Some fungi are opportunistic pathogens and can lead to serious systemic fungal infections. In 2020, more than 150 million cases of severe fungal infections were reported globally resulting in an estimated 1.7 million deaths. Coccidioidomycosis, or Valley fever, is classified as a serious fungal infection caused by the fungi Coccidioides immitis and C. posadasii. These particular fungi are prevalent in the soil of the Southwestern United States, including Las Vegas, Nevada. In 2024, there were a total of 269 cases of Valley fever reported in Nevada, and 239 of those cases were reported in Las Vegas. This study aimed to provide a comprehensive assessment of the airborne concentration of both total fungi and Coccidioides species across different seasons, weather patterns (non-weather vs. weather event), and meteorologic factors (temperature, relative humidity, and wind) in Las Vegas, Nevada. Validation and optimization of a universal fungal PCR assay was conducted using 47 fungal species. The universal fungal PCR assay was able to detect all target fungal species. Two different master mixes (Universal Fast Advanced and TaqPath BactoPure) were tested to determine which one was more effective at overcoming PCR inhibitors. There was a statistically significant difference between the master mixes (p = 0.03). Environmental air samples from 13 sites across Las Vegas were collected in 2022 and analyzed with a validated universal fungal PCR assay and a Coccidioides species PCR assay. Selected samples were collected during high winds/dust advisories. The total concentration of airborne fungi was determined from a composite standard curve that was constructed using the universal fungal PCR assay and DNA from Aspergillus flavus and A. fumigatus. The mean total fungal concentration in the non-weather samples was 754 copies/m3 of air, and 741 copies/m3 of air in the weather event samples. There was no statistically significant difference in the mean concentration of fungi between the two sample types (p = 0.74). There was a significant difference in the mean total fungal concentration between seasons (non-weather p < 0.001; weather event p = 0.03). There was also a significant correlation between total fungi and temperature in the non-weather environmental samples (r = 0.57; p < 0.001). The environmental samples tested (n=185) were negative for Coccidioides DNA. While airborne Coccidioides was not detected at the sampling sites and timeframe of this study, the potential for exposure still exists. This study underscores the need to further understand the environmental distribution of Coccidioides species in Las Vegas, Nevada and its implications for public health. The methodology developed in this study can be used to detect environmental fungi, measure outdoor fungal concentrations, and enhance indoor and outdoor air quality surveillance of microorganisms for public health assessment by providing rapid and quantitative results.

Keywords

Air quality; Airborne fungi; Meteorologic factors; Quantitative PCR; Seasonality; Valley fever

Disciplines

Environmental Health | Environmental Health and Protection | Molecular Biology | Public Health

File Format

pdf

File Size

1599 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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