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Coccidioidomycosis or “cocci” (also known as San Joaquin Valley Fever, desert fever, desert rheumatism or Valley Fever [VF]), has become a silent epidemic caused by individuals inhaling fungal spores of Coccidioides. Coccidioidomycosis is one of the most common lung fungal infections in the United States and has a wide clinical spectrum, ranging from asymptomatic (60%) to a fatal disease. VF got its name from California, where the disease was identified in the central valley as a soil-dwelling fungus. VF is located primarily in US endemic areas of the Arizona, and California, and has gained attention recently from increasing annual cases, and illness migration to other states. VF exposure is driven by a combination of disturbed soil, and heat and drought, which increases the lifecycle of the fungal spore that grows in soil—see Figure 1. Researchers at UC Irvine found that VF incidence in the United States was greater in arid regions due to climate change.

We understand that our current health priorities have been centered on how we manage tobacco, prevent communicable diseases, diminish obesity, and mitigate the hazards of all manner of human conflict. We should now definitively add health matters to the discussion on global climate change, and elevate consideration of the human condition to where it belongs in that discussion—at the top of the list. [A quote from Lemery and Auerbach. Enviromedics 2017]

Figure 1: Life cycle of parasitic and saprobic spores in soil. Source: Wikimedia Commons

Coccidioidomycosis has a long history (Figure 2). It was first identified in 1892. In the 1930s, cocci were identified as a soil fungus that causes respiratory illness from inhalation of aerosol spores.

Figure 2: Timeline of coccidioidomycosis. Source: Source: Hernandez et. al. 2019

Thus, it is our intent to bring awareness to the VF resources, increasing incidence rates in non-endemic regions, testing procedures, treatment options, and prevention/risk mitigation. This is especially true for patients with a history of recent travel to the Southwest region. Research has shown that people who are aware of VF and its symptoms are more likely to request testing, leading to earlier diagnosis and treatment.


In 2019, the US Centers for Disease Control (CDC) reported there were 18,407 cases of VF. The actual number of cases is underestimated since many are not reported to health departments. Furthermore, tens of thousands more VF illnesses maybe misdiagnosed since many are not serologically tested for VF. In highly endemic areas of Arizona, VF causes an estimated 15% to nearly 30% of community-acquired pneumonias, but with low testing rates this figure too is probably underestimated. The CDC reports that approximately 200 deaths per year where coccidioidomycosis was documented as the primary or contributing cause of death.

The geographic distribution of VF includes the southwestern United States (ie, California’s San Joaquin Valley, Arizona’s Sonoran Desert including Phoenix and Tucson as high-risk regions, but to a lesser extent in Nevada, New Mexico, Utah, Texas, and more recently identified in south-central Washington). In 2019, the CDC reported a total of 95,371 coccidioidomycosis cases (2011-2017) from 26 states, and >95% of cases were reported from Arizona (64.5%) and California (32.5%)—see Figure 3. Most cases occurred in in male adults, and the incidence per 100,000 person was twice as high in Black Americans compared to White Americans. Incidence was higher among Hispanics than non-Hispanics in California. Approximately, 5-10% of people infected with VF will develop serious lung problems, and that 1% of infected develop disseminated disease that effects Black Americans disproportionately, suggesting a possible genetic component, and further supporting the phenomenon that climate change-driven health effects disproportionately affect communities of color.

Researchers at the University California Irvine have developed predictive maps for years 2035, 2065 and 2095. By 2095 the endemic regions will increase from 12 to 17 states—see Figure 4. Furthermore, they state that climate change is creating warmer temperatures and less precipitation patterns with a prediction to cause VF expansion north and east into Idaho, Wyoming, Montana, Nebraska, South Dakota, and North Dakota. Rain will inhibit VF from spreading into states farther east and along the central and northern Pacific coast.

Figure 4: Projection of VF expansion by 2095 due to climate change. Source: UCI New

Exposure Risks and Clinical Presentation:

The risk of being infected by VF can occur to anyone who lives or travels to the southwest states, particularly to endemic regions of Arizona and California, Mexico, and Central or South America. The risk of infection is greater during high winds or dust storms during residential activities, occupational exposure during ground excavation, sports/athletic training, military field training, construction and farm workers, agricultural field workers, or during recreation (eg, walking/hiking, trail running, mountain biking, etc). Historically, it is more common in adults aged 60 year or greater, but other age groups are at higher risk for disseminated “cocci” in those with weakened or physiologically changed (pregnant) immune function:

  2. Organ transplant patients
  3. Pregnant women
  4. Diabetics

Valley Fever is not contagious between individuals. As with humans, pets may too be exposed to “cocci” fungus, and dogs make up the majority of VF animal cases. Pets do not always develop VF symptoms when infected, but when they do, they present with coughing, lack of energy and weight loss. It is essential to seek out a veterinarian ensuring early management to prevent long-term complications and death. When people are exposed to VF fungus 60% are mild with little or no symptoms, and are protected from getting VF again. While 30% have moderate and 10% have severe symptoms. If symptoms last more than a week, seek a healthcare provider and get serologic test for VF. See Figure 5 for common signs and symptoms of VF.

The clinical challenge is to make a fast and accurate VF diagnosis since many patients are sent home based on overlapping symptoms with influenza—headache, fever, cough, myalgia and malaise, causing a delay in diagnosis and treatment. Many VF patients often get diagnosed with community acquired bacterial pneumonia and prescribed an antibiotic, but return with worsening symptoms. According to the CDC, these are not isolated incidences of misdiagnosis. Many clinicians outside of the endemic regions do not treat VF and therefore do not routinely consider a differential diagnosis of VF, and all too often patients get misdiagnosed. When a diagnosis is delayed this illness can become disseminated coccidioidomycosis causing destruction in skin, bones, brain tissue and other organs.

Due to heightened concern of COVID-19 infection, many seek medical care for symptoms of fever, chills, cough, shortness of breath, fatigue muscle and body aches. COVID-19 also has overlapping symptoms with VF. These patients will routinely get tested incorrectly, and go undiagnosed for VF for days and weeks due to COVID-19 bias. Early recognition of VF is imperative during COVID-19 pandemic since approximately 75% of VF patients miss work or school for two weeks until more diagnostic tests, e.g., diagnostic lumbar puncture or biopsy, for worsening of symptoms.

Figure 5: Common Valley Fever signs and symptoms. Source: California Department of Public Health

Not all VF patient will be prescribed antifungal medications since many with pulmonary VF get better. Medication will be considered after taking a series of serological tests and chest x-rays along with the severity and duration of symptoms such as weight loss, night sweats, infiltrates in the lungs enlarge, and the inability to work. At that time antifungal medication usually is considered. It is common to prescribe the azole family of antifungal drugs for uncomplicated cocci. These medications are oral preparations of ketoconazole, itraconazole and fluconazole, and each have various side-effects. For more complicated cases, the use of Amphotericin B, an antifungal medication, is used in fulminant infections. Seek out the VF antifungal treatment recommendations, most recently updated in the 2016 Clinical Practice Guideline published by the Infectious Disease Society of America.

Valley Fever Prevention:

The California Department of Public Health recommends the following prevention tips to help avoid breathing in outdoor dust and may help reduce your risk of getting Valley Fever (Table 1).

  • Avoid dust outside in places where Valley Fever is common.
  • Stay inside and keep windows and doors closed when it's windy outside and the air is dusty, especially during dust storms.
  • While driving in areas where Valley Fever is common, keep car windows closed and use recirculating air, if available.
  • Consider avoiding outdoor activities that involve close contact with dirt or dust, including yard work and digging, especially if you are in one of the groups at higher risk for severe or disseminated Valley Fever.
  • Cover open dirt areas around your home with grass, plants, or other ground cover (like gravel or wood chips) to help reduce dusty, open areas.
  • Try to avoid construction or excavation sites. If you cannot avoid these dusty areas, or if you must be outdoors in dusty air, consider wearing an N95 respirator to help protect against dust that can cause Valley Fever. Cloth masks, KN95s (not certified), bandanas, surgical face masks, and simple dust masks are not as protective against dust as N95 masks.
  • Stay upwind of the area where dirt is being disturbed.
  • After returning indoors, change out of clothes if covered with dirt. Be careful not to shake out clothing and breathe in the dust before washing. If someone else is washing your clothes, warn the person before they handle the clothes.

Table 1: Valley Fever risk mitigation tips. Source: California Department of Public Health

There are excellent resources to expand your VF awareness for both the clinician and lay public (Table 2).

Table 2: Valley Fever resources for healthcare professionals and the public.

Final Thoughts:

It is difficult to avoid exposure to Coccidioides, but you can decrease your risk outdoors in endemic regions where you live or travel. Currently, there is no vaccine to prevent infection, but ongoing vaccine research for canines will hopefully transition for use in humans.

Thus, having awareness about VF is the key for healthcare providers and the public during outdoor activities in their communities and in the wilderness in effort to avoid delays in diagnosis, treatment and long-term complications.

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