Determining the effects of ambient dust exposure and extreme dust events on coccidioidomycosis in Arizona

About This Grant

PROJECT SUMMARY Coccidioidomycosis infections cause almost a third of community-acquired pneumonia cases in Arizona, and reported cases have doubled from 2013-2021. Coccidioidomycosis is an infection caused by inhalation of fungal spores from the soil-dwelling Coccidioides genus, and can lead to chronic lung infection, meningitis, or death. The disease is a growing public health concern in the southwestern US, particularly in Arizona, which reports around 10,000 cases per year—nearly two-thirds of US cases. The disease imposes a significant public health and economic burden, with Arizona’s 2019 cases alone estimated to cost $736 million in lifetime expenses. Yet, public health responses have been hindered by critical gaps in understanding of the environmental drivers of infection, particularly the role of dust exposure. Changing hydrometeorological factors, such as increasing aridity and more frequent dust storms, may be contributing to rising incidence, as dust and dust-generating processes (e.g., wind erosion, construction, agriculture) likely promote aerosolization and dispersion of Coccidioides spores. However, the relationship between dust exposure and coccidioidomycosis incidence remains unclear, with some studies linking short-term, extreme dust events to outbreaks and others finding no impact. This project aims to fill these knowledge gaps by leveraging a novel database of spatiotemporally refined dust concentration estimates and all reported coccidioidomycosis cases (n > 126,000) in Arizona from 2005 to 2022. Our secondary data analysis study has three aims: 1) Estimate the effects of daily ambient dust exposure on coccidioidomycosis incidence and identify populations most vulnerable to these exposures, focusing on determinants of social vulnerability such as low income, poor housing quality, and racial/ethnic minorities; 2) Assess the impact of extreme dust events on coccidioidomycosis incidence, and identify populations most vulnerable to these exposures; 3) Investigate whether hydrometeorological factors, including oscillations between wet and dry conditions that may influence spore growth and dispersal, modify the relationship between dust exposures and coccidioidomycosis incidence. Our results will help guide public health messaging and target prevention strategies in Arizona to both the general population and clinicians surrounding when and where risk of coccidioidomycosis transmission is highest; provide important evidence on the contribution of environmental change to transmission; and enable identification of populations and geographies particularly sensitive to dust exposures.