Coccidioidomycosis

球孢子菌病

Evidence-backed information EN 5/7 applicable sections · ZH 5/7 applicable sections Updated Oct 23, 2026

Coccidioidomycosis, also called Valley fever, is a fungal disease of mammals caused by Coccidioides immitis or C. posadasii and is endemic to arid regions of the southwestern United States, northern Mexico, and parts of Central and South America ^[1]^[2]. The infection is typically acquired by inhaling airborne spores released from disturbed soil, and incidence has been rising with expanding recognized geographic range ^[1]^[2]. Most infections are asymptomatic, but pulmonary illness is a leading cause of community-acquired pneumonia in highly endemic areas ^[1]^[2].

Read the full clinical and epidemiological profile 6

Definition

Coccidioidomycosis is an invasive dimorphic fungal infection caused by the pathogens Coccidioides immitis and C. posadasii, which grow as soil mycelia and form spherules in the host ^[1]^[2]. The fungi reside in arid desert soils of the southwestern United States, northern Mexico, and parts of Central and South America ^[1]^[2].

Clinical features

Approximately 60% of infected persons have minimal or no symptoms, while about 40% develop clinical manifestations, most often a respiratory primary infection resembling bronchitis or pneumonia that resolves over weeks ^[1]^[2]. Symptomatic individuals may experience profound fatigue, fever, cough, headaches, rash, muscle and joint pain, and loss of smell and taste, with tiredness sometimes persisting for months ^[1]. Disseminated disease occurs uncommonly, spreading to skin, bones, joints, or central nervous system ^[2].

Epidemiology

Coccidioidomycosis is endemic in Arizona, California, Nevada, New Mexico, Texas, Utah, northern Mexico, and parts of Central and South America ^[1]^[2]. It is a common cause of community-acquired pneumonia in endemic US regions, accounting for roughly 20% of such cases locally ^[1]. Incidence is increasing likely due to climatic and population changes, and the recognized distribution is expanding into new areas such as eastern Washington, Oregon, and Utah ^[2]. Wind-driven dispersal from endemic zones has produced outbreaks hundreds of miles away, as in a 1977 California windstorm causing several hundred cases ^[1].

Transmission

Transmission occurs through inhalation of arthroconidial spores that become airborne when soil is disrupted by natural events such as earthquakes, dust storms, fires, or windstorms, and by human activities including construction, farming, military maneuvers, recreation, and agriculture ^[1]^[2]. The disease is not contagious between persons ^[1].

Prevention

No fully effective preventive measures exist for residents or travelers in endemic areas, though avoiding airborne dust or dirt is recommended and does not guarantee protection ^[1]. Workers in certain occupations may be advised to use face masks to reduce exposure ^[1]. Enhancing surveillance and improving early diagnostics are considered key public-health measures for preparedness in endemic regions ^[1].

References

1 Wikipedia contributors. Coccidioidomycosis - Wikipedia [Internet]. Wikipedia. cited 23 Oct 2026. Available from: https://en.wikipedia.org/wiki/Coccidioidomycosis
2 Crum NF et al. Coccidioidomycosis: A Contemporary Review. Infect Dis Ther. 2022 Apr. PMID: 35233706. doi: 10.1007/s40121-022-00606-y. PubMed: https://pubmed.ncbi.nlm.nih.gov/35233706/
3 Bays DJ et al. Coccidioidomycosis. Infect Dis Clin North Am. 2021 Jun. PMID: 34016286. doi: 10.1016/j.idc.2021.03.010. PubMed: https://pubmed.ncbi.nlm.nih.gov/34016286/
4 Thompson GR 3rd et al. Global guideline for the diagnosis and management of the endemic mycoses: an initiative of the European Confederation of Medical Mycology in cooperation with the International Society for Human and Animal Mycology. Lancet Infect Dis. 2021 Dec. PMID: 34364529. doi: 10.1016/S1473-3099(21)00191-2. PubMed: https://pubmed.ncbi.nlm.nih.gov/34364529/