Fungal Infections


Species name, teleomorph and common name

Coccidioides immitis and Coccidioides posadasii

Natural habitat

Soil with a restricted geographical distribution. Endemic to lower sonoran desert ecozone.


Primarily hot, arid areas of southwestern USA, northern Mexico and focal areas of Central and South America (see map).


Rarely isolated from soil, certain ‘hot spots’ have been identified because of the higher frequency of diseases. As only 40% of those infected develop disease and ~25,000 new, clinical cases of coccidioidomycosis are reported annually, this implies ~60,000 infections annually in the USA. Probably similar numbers occur in central and south America.

For accidental lab infection   view here


Coccidioidomycosis refers to disease caused by either of the above species. Infection may be a self-limited primary infection (often called Valley Fever after the San Joaquin Valley in central California) or pneumonia.  Subsequently other progressive forms of coccidioidomycosis occur including:

  •  Meningitis
  •  Disseminated disease to the skin, lymph nodes, bone, or any other body site
  •  Nodule in the lung
  •  Chronic cavitary pulmonary coccidioidomycosis .

Culture peculiarities

C. immitis grows on many fungal media in 2-7 days, but poorly, or not at all, on standard bacterial media such as blood agar. C. immitis is difficult to culture from blood and cerebrospinal fluid, even in the context of disseminated disease or meningitis.

Antifungal resistance (intrinsic and acquired)

Coccidioides immitis is susceptible to most antifungal agents except terbinafine and flucytosine. The agents of choice for treatment include amphotericin B for very ill patients, itraconazole, fluconazole and posaconazole.

Biosafety level 3

Coccidioides spp. are Biosafety level 3 pathogens and must be managed accordingly.

Industrial use




Electron microscopy of Coccidioides immitis showing characteristic arthrospores.

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