A Review of Coccidioidomycosis in California: Exploring the Intersection of Land Use, Population Movement, and Climate Change

Abstract

California has seen a surge in coccidioidomycosis (valley fever), a disease spread by the Coccidioides immitis fungus found in soil throughout the state, particularly in the San Joaquin Valley. We reviewed epidemiologic studies in which outbreak and sporadic cases of coccidioidomycosis were examined, and we considered the possible relationship of these cases to environmental conditions, particularly the state’s increasing aridity, drought, and wildfire conditions. Most of the studies we reviewed pertained to cases occupationally acquired in construction, military, archeological, and correctional institutional settings where workers were exposed to dust in C. immitis–endemic areas. A few reviewed outbreaks in the general population related to dust exposure from natural disasters, including an earthquake-associated landslide and a dust storm that carried particles long distances from endemic areas. Although many of California’s coccidioidomycosis outbreaks have been occupationally related, changing demographics and new, immunologically naïve populations in dry, endemic areas could expose the general population to C. immitis spores. Given the high rate of infection among workers who, for the most part, are healthy, the general population, including some elderly and immunocompromised individuals, could face additional risk. With climate-related events like drought and wildfires also increasing in endemic areas, research is needed to address the possible associations between these phenomena and coccidioidomycosis outbreaks.

Regional Analysis of Coccidioidomycosis Incidence — California, 2000–2018

“…In contrast, coccidioidomycosis risk in Hispanics compared with that in Whites and in adults aged 40-59 years compared with that in persons aged <20 years varied by region, suggesting that infection in these groups might be more influenced by environmental exposures in certain regions, possibly related to work or recreational outdoor activities, particularly those involving dirt or dust. The majority of coccidioidomycosis outbreaks in California have occurred in high-incidence regions and have been associated with dirt-disturbing work settings, including construction, military, archeologic sites, and correctional institutions, where high attack rates have been seen even among relatively young, Age-adjusted rate ratios healthy populations (10). Further research is needed to better delineate the factors associated with increased risk in these groups in some but not all regions.…”

No Consistent Link Between Dust Storms and Valley Fever (Coccidioidomycosis)

“…COMRIE 10.1029/2021GH000504 3 of 17 infection rates (Pearson et al, 2019). A vaccine is still in development, although the disease is treatable with antifungal drugs and deaths are relatively rare (Ampel, 2020).…”

“…The fungus forms spherules, specialized structures that produce and release hundreds of endospores, which in turn disperse and multiply, spreading primarily as a pulmonary infection, although it can disseminate to other organs. Annual human case counts can exceed 20,000 per year in the US, with naïve populations susceptible to higher infection rates (Pearson et al., 2019 ). A vaccine is still in development, although the disease is treatable with antifungal drugs and deaths are relatively rare (Ampel, 2020 ).…”

Update on Coccidioidomycosis in the United States and Beyond

“…Efforts to reduce dust during construction should be implemented. 35 Education for clinicians is also essential. Pediatricians in endemic areas should consider coccidioidomycosis in their differential diagnoses in children presenting with chronic cough, prolonged fever, pneumonia that is not responsive to appropriate anti biotics, culture-negative meningitis or osteomyelitis.…”