for Prevention

Increased Coccidioidomycosis (“Valley Fever”) in Los Angeles County

Benjamin Schwartz, MD

Dawn Terashita, MD, MPH

July-August 2017

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Coccidioidomycosis, commonly known as “Valley Fever,” is an infection caused by inhalation of spores from the fungus Coccidioides that lives in dry soil and dust. The number of reported coccidioidomycosis cases have increased in Los Angeles County and in California in the past several years. In 2016, there were 714 reported cases in LA County, compared with 522 in 2015, a 37% increase. Each year since 2009, the number of reported coccidioidomycosis cases has increased annually and the total number of reports has increased 3-fold. While cases are reported from throughout the county, most cases have occurred in northern areas, specifically Antelope Valley and San Fernando Valley. Overall, the rate of coccidioidomycosis in LA County is about 7 cases per 100,000 people; among residents of Antelope Valley the rate is about 9-fold higher than elsewhere in the county. California is also seeing a significant increase in the number of cases reported statewide. The highest rate of infection in the state is in Kern County, immediately to the north of LA County (see map).

Possible reasons for the increase in disease include changes in weather and rainfall as well as persons moving into new developments in areas of higher risk. Changes in surveillance also may be contributing to increased case numbers with more cases being reported through an electronic laboratory reporting system.

Given the increase in risk of coccidioidomycosis, it is important for LA County providers to be familiar with this infection. A summary of coccidioidomycosis transmission, clinical characteristics, diagnosis, management, and prevention is presented below. For more detailed clinical guidance, please see the reference documents at the end of this article.

Key Messages

  • Between 2015 and 2016, the number of reported coccidioidomycosis cases in Los Angeles County increased 37%. California also saw significantly more cases.
  • Clinicians should consider coccidioidomycosis in any patient with a compatible clinical syndrome such as community acquired pneumonia who resides in, works in, or travels to an endemic area including parts of Los Angeles County (Antelope Valley and the west and north parts of the San Fernando Valley).



Coccidioidomycosis is typically caused by the inhalation of spores from fungal species belonging to the Coccidioides genus from airborne dust or soil (see Biology of Coccidioidomycosis). The risk of infection is greater when the soil is disrupted such as during strong winds, dust storms, build­ing construction, agriculture, earthquakes, and archaeological digs. It is not transmitted person-to-person.

Biology of Coccidioidomycosis



The fungi are endemic to the southwestern United States (i.e. Arizona, California, Nevada, New Mexico, Texas, and Utah) and parts of Central and South America. Highly endemic areas include the San Joaquin Valley in California and southern Arizona as shown in the maps below.


Areas Endemic for Coccidioidomycosis

  Map of areas endemic for Coccidiodomycosis



This map is based on studies performed in the late 1940s and 1950s and also on locations of more recent outbreaks and cases. Coccidioides might also be found in similar areas with hot, dry climates that are not shaded on the map.






Annual Rates of Valley Fever, California 2011-2015

  Annual rates of valley fever in California



Rates calculated per 100,000 population






Clinical Picture

About 60% of infected people do not develop any symptoms. Among those who are symptomatic, typically beginning one to three weeks after exposure to the spores, a spectrum of symptoms and signs may occur (see box below). 


Symptoms and Signs of Primary Coccidioidomycosis

  • Fever
  • Fatigue
  • Night sweats
  • Cough
  • Chest pain
  • Dyspnea
  • Hemoptysis
  • Headache
  • Arthralgia
  • Erythema nodosum
  • Erythema multiform


Valley fever is the most common presentation and can include a self-limited flu-like illness and/or community acquired pneumonia (CAP) with fever, cough, chest pain, and headache. Systemic complaints — which include fatigue, myalgia, arthralgia, and night sweats may last for weeks to months. Erythema nodosum and erythema multiforme also may occur. Chest radiograph findings may include diffuse pulmonary infiltrates, hilar adenopathy, and pleural effusion.

Complications are rare but can be severe. Approximately 5-10% of infections result in significant pulmonary disease and less than 1% result in extra-pulmonary disseminated disease that can involve multiple organ systems, last life-long, and lead to outcomes such as meningitis and death. Risk factors for severe or disseminated disease include immunosuppression (e.g. HIV/AIDS, TNF inhibitors, chemotherapy), diabetes mellitus, and pregnancy. In addition, some groups are at higher risk for complications including the elderly, African Americans, and persons of Filipino ethnicity.



Coccidioidomycosis should be considered in any patient with a compatible clinical syndrome who resides in, works in, or has traveled to an endemic area including Antelope Valley, the north and west parts of the San Fernando Valley, Kern County, Ventura County, California’s Central Valley (San Joaquin Valley), and southern Arizona. Providers should note any exposure to airborne dust or soil from the endemic areas. History should also include location and type of work as cases and outbreaks have resulted from work exposures. Prolonged illness or CAP unresponsive to antimicrobial therapy increases the likelihood of coccidioidomycosis. In endemic areas, clinicians should consider testing for coccidioidomycosis in patients who initially present with CAP (especially during seasons when other causes are less common) as an accurate diagnosis may reduce unnecessary exposure to antibiotics and facilitate appropriate counseling and possible therapy.

Serologic tests to detect IgM and IgG antibodies are used most often to diagnose coccidioidomycosis. Although cough associated with coccidioidomycosis generally is non-productive, if sputum can be obtained, direct examination of a smear with potassium hydroxide (KOH) or culture may be positive. The organism also may be identified by culture of tissue.



There is currently no evidence that treatment of uncomplicated coccidioidal infections reduces symptom duration or prevents complications; therefore, most immunocompetent patients with mild symptoms will not require antifungal therapy. Supportive care should be provided as needed. Symptoms of prolonged fatigue can be managed by physical therapy for re-conditioning.

Antifungal therapy should be started for patients with significantly debilitating illness or who are in groups at higher risk for disseminated disease or adverse outcomes: this includes persons with diabetes mellitus, who are immunocompromised, pregnant women, and the frail elderly. Per the 2016 Infectious Disease Society of America (IDSA) Clinical Practice Guideline for the Treatment of Coccidioidomycosis, treatment may be considered in demographic groups at higher risk for disseminated disease, e.g. African Americans and Filipinos. Generally, treatment is with an oral azole antifungal although in some groups amphotericin B is recommended. As detailed treatment recommendations are beyond the scope of this article, clinicians should refer to the IDSA guideline for more information. In general, primary care providers should consult with specialists if considering initiating treatment.



Valley fever patient information leaflet

There are no clearly effective interventions to prevent coccidioidomycosis for persons living or working in endemic areas. Approaches to reduce the risk of breathing in the fungal spores include staying inside with windows and doors closed when it is dusty outside, keeping car windows closed and using recirculating air conditioning while driving, and wearing an N95 mask if exposure to a high volume of dust that cannot be avoided.

Patient education materials are available from the Los Angeles County Department of Public Health (DPH). Employers who have staff with work exposures in endemic areas should maintain a comprehensive approach to minimize dust exposure including the use of respiratory protection.

Resources for preventing work-related Valley Fever are available from the Occupational Health Branch at the California Department of Public Health.


Disease Reporting

Providers in California must report coccidioidomycosis within 7 calendar days from identification (Title 17, CCR, Section 2500). For cases in LA County, reports should be submitted:

For more information or questions regarding coccidioidomycosis, call the DPH Acute Communicable Disease Control Program at 213-240-7941.



Additional Resources


Reference Documents


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Author Information:

Benjamin Schwartz, MD
Interim Director

Dawn Terashita, MD, MPH
Interim Deputy Director

Acute Communicable Disease Control Program

County of Los Angeles
Department of Public Health

Rx for Prevention, 2017

Published: July 29, 2017