Coccidioidomycosis

Coccidioidomycosis is a mammalian fungal disease caused by the dimorphic saprophytic fungi Coccidioides immitis or Coccidioides posadasii. The organism exists as a mycelial form in soil and transforms into a spherule form within host tissues. The disease is commonly known by the colloquial terms 'cocci,' 'Valley fever,' or 'San Joaquin Valley fever' in affected regions of North America.

Approximately 60% of infected individuals experience minimal to no symptoms, while 40% develop clinical illness typically manifesting as a respiratory syndrome resembling bronchitis or pneumonia. Common symptoms include fever, cough, fatigue, headache, rash, myalgia, and arthralgia, with notable loss of smell and taste reported. Fatigue may persist for many months following acute infection. In endemic areas, coccidioidomycosis accounts for approximately 20% of community-acquired pneumonia cases. The disease may progress from acute Valley fever to chronic pulmonary forms and potentially to disseminated infection, which can involve the skin, bones, joints, heart, genitourinary tract, and meninges, with potentially fatal outcomes.

Coccidioidomycosis is endemic to discrete geographic regions including the southwestern United States—specifically Arizona, California, Nevada, New Mexico, Texas, and Utah—as well as northern Mexico and parts of Central and South America. The fungus resides in soil of these areas, particularly California and Arizona, and becomes environmentally active following rainfall after prolonged dry periods. Windstorms have demonstrated capacity to disperse infectious spores over hundreds of miles, as exemplified by a December 1977 windstorm near Arvin, California that generated cases including fatalities in non-endemic regions distant from the source area.

Infection occurs through inhalation of airborne arthroconidia, the infectious spore form of Coccidioides species. These spores are released into the air when soil is disrupted by activities such as construction, agricultural work, dust storms, seismic events, or other disturbances that fragment the mold filaments. The fungus is not transmitted person-to-person; Valley fever is explicitly characterized as a non-contagious disease. Environmental aerosolization during wind events represents the primary exposure mechanism for both endemic acquisition and epidemic spread beyond traditional boundaries.

Individuals with compromised immune systems face elevated risk for severe disease manifestations including severe pneumonia with respiratory failure, lung nodule formation, and disseminated infection. The disseminated form can produce devastating multi-organ involvement affecting the skin, skeletal system, cardiovascular system, and central nervous system.

Source-backed prevention guidance is not yet available in the provided source material. General exposure control principles would logically focus on limiting inhalation of airborne dust in endemic areas, particularly during activities that disturb soil or during wind events in known endemic regions.

In endemic areas, coccidioidomycosis should be considered in all cases of community-acquired pneumonia, as it represents a substantial etiologic fraction of such presentations. Surveillance systems should incorporate awareness of windstorm events as potential harbingers of case increases, including in geographic areas not traditionally classified as endemic. The non-contagious nature of the disease simplifies contact tracing but requires emphasis on environmental exposure assessment in case investigations.

1. 1 Wikidata. coccidioidomycosis.
2. 2 Wikipedia. Coccidioidomycosis - Wikipedia.

ICD-10

ICD-11

Total cases

160K

Peak month

2024-03

Coverage

2 reporting countries · 2012-09-14 → 2026-05-09