Combining Forces - The Use of Landsat TM Satellite Imagery, Soil Parameter Information, and Multiplex PCR to Detect Coccidioides immitis Growth Sites in Kern County, California

Abstract

Coccidioidomycosis is a fungal disease acquired through the inhalation of spores of Coccidioides spp., which afflicts primarily humans and other mammals. It is endemic to areas in the southwestern United States, including the San Joaquin Valley portion of Kern County, California, our region of interest (ROI). Recently, incidence of coccidioidomycosis, also known as valley fever, has increased significantly, and several factors including climate change have been suggested as possible drivers for this observation. Up to date details about the ecological niche of C. immitis have escaped full characterization. In our project, we chose a three-step approach to investigate this niche: 1) We examined Landsat-5-Thematic-Mapper multispectral images of our ROI by using training pixels at a 750 m×750 m section of Sharktooth Hill, a site confirmed to be a C. immitis growth site, to implement a Maximum Likelihood Classification scheme to map out the locations that could be suitable to support the growth of the pathogen; 2) We used the websoilsurvey database of the US Department of Agriculture to obtain soil parameter data; and 3) We investigated soil samples from 23 sites around Bakersfield, California using a multiplex Polymerase Chain Reaction (PCR) based method to detect the pathogen. Our results indicated that a combination of satellite imagery, soil type information, and multiplex PCR are powerful tools to predict and identify growth sites of C. immitis. This approach can be used as a basis for systematic sampling and investigation of soils to detect Coccidioides spp.

The Changing Epidemiology of Coccidioidomycosis in Los Angeles (LA) County, California, 1973–2011

“…Recently, researchers detected Coccidioides in Washington State soil for the first time[ 36 ]. Other than drought and the expansion of land development and human populations into endemic areas, ecologic changes in soil and climate change might have contributed to increases in LA County and in the United States[ 37 , 38 ]. Between 2003 and 2005 several California counties also had an increase in cases[ 39 ].…”

“…Development can involve any soil-disturbing activity including environmental cleanup. Other than epidemiologic data, ecologic studies with soil testing and geological maps on soil type can inform development planning when soil disturbance is proposed in endemic areas and nearby areas not known to be endemic for Coccidioides [ 37 ]. Planning should involve local residential communities and businesses when developing and executing education and prevention strategies to minimize exposure of residents and traveling visitors.…”

Coccidioides immitis and posadasii; A review of their biology, genomics, pathogenesis, and host immunity

“…grow in the arid, alkaline desert soil in California, but soil is very complex [9] and the characteristics of contaminated soil may differ between endemic regions [10]. So far, no one set of physical, biological, and chemical characteristic describes all the sites where the organism has been found, and even in one “site” the fungus is distributed unevenly in the soil for unclear reasons.…”

Exploring the Distribution of Coccidioides immitis in South Central Washington State

“…Colonization of soils by C. immitis has been confirmed at exposure sites associated with these cases 1 . Multiple studies have identified a relationship between environmental conditions and C. immitis growth areas 2,3,4 , but these relationships have not been evaluated in Washington. The Washington State Department of Health has been conducting environmental surveillance in an effort to understand the geographic distribution of C. immitis in central Washington and the associated risk to humans and animals.…”