What is coccidioidomycosis?

Updated: Aug 27, 2019
  • Author: Duane R Hospenthal, MD, PhD, FACP, FIDSA, FASTMH; Chief Editor: Michael Stuart Bronze, MD  more...
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Coccidioidomycosis is caused by Coccidioides immitis, a soil fungus native to the San Joaquin Valley of California (see the image below), and by C posadasii, which is endemic to certain arid-to-semiarid areas of the southwestern United States, northern portions of Mexico, and scattered areas in Central America and South America. Although genetically distinct, the 2 species are morphologically identical.

A Coccidioides immitis spherule containing endospo A Coccidioides immitis spherule containing endospores. Courtesy of Thomas Matthew.

Few immunologic differences are noted between the 2 species of Coccidioides, and the manifestations of infection with either organism are assumed to be identical; however, this hypothesis has not been formally tested. For all intents and purposes, all subsequent references to C immitis in this article also apply to C posadasii.

See A Chronic, Scaly Rash Mistaken for MRSA: Case Presentation, a Critical Images slideshow, to review additional images and details of a case of Coccidioidomycosis.

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