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ISDS 2016 Conference Abstracts

Exploring the Distribution of Coccidioides immitis in 
South Central Washington State
Wayne Clifford*
Department of Health, Washington State, Olympia, WA, USA

Objective
Our objective is to describe the environmental conditions associated 

with confirmed Coccidioides immitis growth and accumulation sites 
in south central Washington in an effort to understand the ecology and 
identify additional potential sites across this emerging endemic zone.

Introduction
Coccidioidomycosis, commonly referred to as Valley Fever, is 

caused by the soil-borne saprophytic fungus C. immitis and posadasii. 
These species have historically been found in the desert southwest and 
Mexico; however, in 2010 there were three coccidioidomycosis cases 
identified in central Washington. Colonization of soils by C. immitis 
has been confirmed at exposure sites associated with these cases1. 
Multiple studies have identified a relationship between environmental 
conditions and C. immitis growth areas2,3,4, 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. 
Here we describe our environmental surveillance efforts and present 
preliminary findings related to environmental conditions of C. immitis 
growth areas in central Washington.

Methods
We collected soil samples at potential human exposure sites in 

central Washington, as identified through clinical surveillance and 
patient interviews. Soil samples were also collected from areas 
not associated with human cases by looking for similar soils in 
areas of interest Soil samples are analyzed by the U.S. Centers for 
Disease Control and Prevention using real-time PCR that detects 
Coccidioides-specific targets. We employed data from the USDA Soil 
Survey Geographic (SSURGO) database to describe environmental 
conditions associated with positive samples. We used our findings 
to identify un-sampled regions of central Washington that could 
potentially support C. immitis growth.

Results
We detected Coccidioides in 13 soil sampling sites at five 

locations withing the region. These detections included locations not 
previously described in central Washington. We identified a band 
stretching across central Yakima and Benton counties with similar 
soil characteristics to our positive sample sites, which suggests these 
regions could potentially support the growth of C. immitis.

Conclusions
Coccidioidomycosis is emerging in south central Washington, and 

the ecology and geographic distribution of the pathogen are poorly 
understood. We found that C. immitis presents a risk to humans and 
animals across a larger region of central Washington than previously 
described and highlights a need for continued environmental 
surveillance. The potential growth sites we identified also provide 
a valuable tool for human and veterinary health care providers and 
public health practitioners to understand and mitigate disease risk.

Keywords
Valley Fever; Coccidioides; Spatial Analysis; Environmental 
Surveillance

Acknowledgments
Centers for Disease Control and Prevention, Mycotic Disease Branch, 
Atlanta, Georgia.
United States Geological Survey, St. Petersburg, Florida

References
1. Litvintseva, Anastasia P, Nicola Marsden-Haug, Steven Hurst, Heather 

Hill, Lalitha Gade, Elizabeth M Driebe, Cindy Ralston, Chandler 
Roe, Bridget M Barker, and Marcia Goldoft. 2015. “Valley Fever: 
Finding New Places for an Old Disease: Coccidioides Immitis Found 
in Washington State Soil Associated with Recent Human Infection.” 
Clinical Infectious Diseases 60 (1): e1–3.. Baptista Rosas, Raul C, 
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Modeling of Coccidioides Spp. in Western North American Deserts.” 
Annals of the New York Academy of Sciences 1111 (1): 35–46.

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3. Fisher, Frederick S, Mark W Bultman, Suzanne M Johnson,
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4. Lauer, Antje, Jorge Talamantes, Laura Rosío Castañón Olivares, Luis
Jaime Medina, Joe Daryl Hugo Baal, Kayla Casimiro, Natasha Shroff, 
and Kirt W Emery. 2014. “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.” PloS One 9 (11): e111921.

*Wayne Clifford
E-mail: wayne.clifford@doh.wa.gov

Online Journal of Public Health Informatics * ISSN 1947-2579 * http://ojphi.org * 9(1):e10, 2017