''CoccidioidesC. immitis'', along with its relative ''[[Coccidioides posadasii|C. posadasii]]'',<ref>{{cite web | url=http://www.broadinstitute.org/annotation/genome/coccidioides_group/MultiHome.html|title=Coccidioides group database | publisher=Broad Institute | accessdate=11 July 2013}}</ref> is most commonly seen in the desert regions of the southwestern United States, including certain areas of Arizona, California, New Mexico, Nevada, Texas, and Utah; and in Central and South America in Argentina, Brazil, Colombia, Guatemala, Honduras, Mexico, Nicaragua, Paraguay, and Venezuela.<ref>{{cite web | url=http://geopubs.wr.usgs.gov/open-file/of00-348/of00-348.pdf | title=Operational Guidelines (version 1.0) for Geological Fieldwork in Areas Endemic for Coccidioidomycosis (Valley Fever) | publisher=[[U.S. Department of the Interior]] | work=U.S. Geological Survey Open-File Report 00-348 Version 1.0 | accessdate=12 July 2013 | author=Frederick S. Fisher, Mark W. Bultman, and Demosthenes Pappagianis}}</ref> ''C. immitis'' is largely found in California, while ''C. posadasii'' is endemic to Texas, northern Mexico and in Central and South America. Both ''C. immitis'' and ''C. posadasii'' are present in Arizona.<ref name="Human Mycoses">Hospenthal, Duane R., and Michael G. Rinaldi. Diagnosis and Treatment of Human Mycoses. Totowa, N.J.: Humana Press, 2007, p. 296-297.</ref>
