ABSTRACT
Coccidioides immitis and Coccidioides posadasil are saprophytic fungi with a dimorphic mode of growth in humans and in the soil. The organisms are endemic to arid regions in the southwestern United States, Mexico, Central America, and South America. C. immitis is geographically limited to the San Joaquin valley region in California. C. posadasil is found in the desert region of the southwestern United States, Mexico, and South America. With the significant population growth in the Sunbelt states, coccidioidomycosis has become a welldefined endemic disease. An estimated 100,000 diseases occur annually in the United States. Disease is a tip-ofthe-iceberg phenomenon compared to the true incidence of infections. Even when disease occurs, the great majority of cases are not properly diagnosed.
