Member species are the cause of coccidioidomycosis, also known as San Joaquin Valley fever, an infectious fungal disease largely confined to the Western Hemisphere and endemic in the Southwestern United States.

The most common clinical syndrome in the other 40% of infected patients is an acute respiratory illness characterized by fever, cough, and pleuritic pain.

[4] Both C. immitis and C. posadasii were viewed as desert saprophytes, but recent genomic research revealed Coccidioides species to have evolved interacting with their animal hosts.

[5] The soil fungus Coccidioides was discovered in 1892 by Alejandro Posadas, a medical student, in an Argentinian soldier with widespread disease.

In 1896, Gilchrist and Rixford named the organism Coccidioides ("resembling Coccidia") immitis (Latin for “harsh,” describing the clinical course).