Coccidioides posadasii

Coccidioides posadasii is a fungus, which is the pathogen o the disease coccidioidomycosis. It has sufficient epidemic danger to be listed in the Select Agent Program. Other names for the disease it causes include The disease has numerous designations related to the location in which it is acquired (eg, valley fever, San Joaquin fever, desert fever, California fever) or clinical manifestations with which it presents (eg, desert rheumatism, coccidioidal granuloma). Most often, the symptomatic infection is referred to as cocci.

Coccidioides immitis and Coccidioides posadasii are dimorphic fungi endemic to certain arid regions in the southwestern United States and in Mexico, Central America, and South America. The 2 species are morphologically identical but genetically and epidemiologically distinct. C immitis is geographically limited to California's San Joaquin valley region, whereas C posadasii is found in the desert southwest of the United States, Mexico, and South America. The manifestations of exposure to either organism are assumed to be identical; however, this hypothesis has not been formally tested.