Classification: ICD-9 114; ICD-10 B38
Synonyms: Valley fever, San Joaquin fever, Desert fever, Desert rheumatism, California disease.
Agent: Coccidioides immitis (Californian) and C. posadasii (non-Californian), dimorphic, soil-borne, ascomycete fungi unique to the western hemisphere.
Reservoir: Dry, sandy alkaline soil in the semi-arid zones of the USA–Mexico border and parts of Central and South America. In North America, the fungus is mainly found in the Lower Sonoran Life Zone with low rainfall and high temperatures C. immitis is present in California, and probably northern Mexico and Arizona, and C. posadasii is present in the remaining areas.
Transmission: Inhalation of arthroconidia (reproductive spores) from the environment or dusty fomites. Sometimes through direct inoculation or transplantation. Person-to-person transmission is extremely rare.
Cycle: The fungal agent reproduces asexually; the mold forms arthroconidia that are aerosolized and can germinate into new mycelia under appropriate conditions. Arthroconidia are infectious when inhaled by an animal or human (accidental hosts). In the lung the arthroconidia convert to spherules in which endospores can develop untill the spherule ruptures and the endospores are released, forming new spherules.
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