Valley Fever is a fungal infection caused by Coccidioides, contracted when people inhale contaminated dust. It’s most common in hot, dry regions like Arizona and California’s Central Valley, where case counts have climbed nationally. This page walks through how illness and test results change over time, which symptoms can appear, and why pregnancy or immunocompromised status raises the stakes. You’ll also see prevention tips for dry, windy seasons and treatment options depending on disease severity.
Key Takeaways
- Serum IgM detected in 70-90% of acute cases within 1-3 weeks
- IgG serology positive in >95% of disseminated Valley Fever by 6 weeks
- Chest X-ray shows infiltrates in 40% of symptomatic primary infections
- In 2022, Arizona reported 26,125 cases of coccidioidomycosis (Valley Fever), the highest annual total ever recorded in the state
- California's San Joaquin Valley accounted for approximately 70% of all Valley Fever cases in the state in 2021
- The national incidence of Valley Fever in the US increased from 5.3 cases per 100,000 in 2011 to 11.2 per 100,000 in 2021
- N95 masks reduce exposure risk by 95% in high-risk occupations
- Avoid dusty activities during dry windy seasons (Oct-May) in endemic areas
- Wet soil before digging reduces spore aerosolization by 90%
- Annual cost of Valley Fever in AZ exceeds $100 million in medical care
- Common symptoms include fever (70%), cough (75%), and fatigue (90%) in symptomatic Valley Fever cases
- Erythema nodosum occurs in 20-30% of primary Valley Fever infections
- Arthralgias affect 40-50% of patients with acute Valley Fever
- Azoles (fluconazole, itraconazole) are first-line for all forms except mild acute
- Fluconazole 400mg daily lifelong for coccidioidal meningitis (90% response)
Rising Valley Fever cases demand quick testing and prevention since symptoms vary and high risk exposure is largely preventable.
Related reading
01 · Category
Diagnosis25 stats
01
Serum IgM detected in 70-90% of acute cases within 1-3 weeks
02
IgG serology positive in >95% of disseminated Valley Fever by 6 weeks
03
Chest X-ray shows infiltrates in 40% of symptomatic primary infections
04
PCR sensitivity for Coccidioides in sputum is 60-80%
05
Culture positivity rate from respiratory specimens is 50-70% in acute disease
06
CSF glucose <40 mg/dL in 70% of coccidioidal meningitis cases
07
Complement fixation titer >1:16 predicts dissemination risk >20%
08
Tuberculin skin test false-positive in 20-25% due to cross-reactivity
09
Bronchoalveolar lavage PCR sensitivity 91% for pulmonary coccidioidomycosis
10
Histopathology shows spherules (10-80 μm) diagnostic in 100% of tissue biopsies
11
IDSA recommends two positive serologies for diagnosis confirmation
12
Urine antigen detection sensitivity 73% in disseminated disease, 27% in non-disseminated
13
False-negative serology in 5-10% of immunocompromised patients
14
CT scan shows nodules/cavities in 80% of chronic fibrocavitary disease
15
Eosinophilia (>5%) in peripheral blood in 25% of primary cases
16
Beta-D-glucan assay non-specific, positive in <50% Coccidioides cases
17
Spinal fluid CF titer >1:2 diagnostic for meningitis (sensitivity 75%)
18
Galaxy morphotype on fungal culture diagnostic for Coccidioides
19
Quantitative CF titer correlates with disease severity (r=0.7)
20
Immunodiffusion IgM sensitivity 83%, specificity 90%
21
PET-CT useful for detecting extrapulmonary dissemination in 90% cases
22
Skin testing no longer available since 1990s due to anaphylaxis risk
23
Enzyme immunoassay (EIA) screening followed by ID/CF reflex, per IDSA
24
Sputum culture conversion lags serology by 3-6 months in 70% cases
25
MRI shows basilar enhancement in 85% of coccidioidal meningitis
Interpretation
Diagnosis Interpretation
For diagnosis, early testing can be quite revealing because serum IgM is positive in 70 to 90% of acute valley fever within 1 to 3 weeks while PCR from sputum detects Coccidioides in 60 to 80% and culture from respiratory specimens is positive in 50 to 70%.
02 · Category
Epidemiology30 stats
01
In 2022, Arizona reported 26,125 cases of coccidioidomycosis (Valley Fever), the highest annual total ever recorded in the state
02
California's San Joaquin Valley accounted for approximately 70% of all Valley Fever cases in the state in 2021
03
The national incidence of Valley Fever in the US increased from 5.3 cases per 100,000 in 2011 to 11.2 per 100,000 in 2021
04
Kern County, California, had an incidence rate of 112.5 cases per 100,000 population in 2020
05
From 2018-2022, Pima County, Arizona, reported over 10,000 cases, averaging 2,000 annually
06
Sonora, Mexico, reported 1,200 Valley Fever cases in 2021 with an incidence of 28 per 100,000
07
In 2019, New Mexico had 1,147 confirmed cases, a 20% increase from 2018
08
Washington state saw 49 cases in 2022, mostly travel-related
09
Utah reported 128 cases in 2021, up from 68 in 2020
10
Texas had 85 cases in 2021, primarily in West Texas counties
11
Nevada reported 189 cases in 2022, incidence of 6.1 per 100,000
12
In 2020, Maricopa County, AZ, had 11,452 cases, 44% of state's total
13
Fresno County, CA, incidence was 94.3 per 100,000 in 2019
14
Over 60% of Valley Fever cases in Arizona occur in individuals aged 20-59 years
15
Males accounted for 61% of Valley Fever cases in California in 2021
16
African Americans have a dissemination rate of up to 15% for Valley Fever, compared to 1% in general population
17
Incidence among Filipinos in California is 165 per 100,000, 10 times higher than whites
18
Pregnant women have a 270% increased risk of disseminated Valley Fever
19
Diabetics have 3 times higher risk of severe Valley Fever
20
HIV patients have up to 50% mortality from disseminated coccidioidomycosis
21
Construction workers face 40 times higher risk of Valley Fever infection
22
60% of primary Valley Fever infections are asymptomatic
23
Annual US cases exceed 60,000, with underreporting estimated at 30-50%
24
Arizona's incidence peaked at 107 per 100,000 in 2011
25
California's cases tripled from 1,000 in 2000 to over 5,000 in 2019
26
40% of cases in Arizona are among non-residents/visitors
27
Children under 5 have lower dissemination rates (<0.5%)
28
Incidence in Arizona Hispanics is 1.5 times higher than non-Hispanics
29
Over 20,000 hospitalized Valley Fever cases annually in US Southwest
30
75% of US cases occur in Arizona and California
Interpretation
Epidemiology Interpretation
Epidemiology trends show Valley Fever is rising in the US, with national incidence climbing from 5.3 cases per 100,000 in 2011 to 11.2 per 100,000 in 2021, while hot spots persist such as Arizona reaching a record 26,125 cases in 2022 and Kern County, California, posting 112.5 cases per 100,000 in 2020.
03 · Category
Prevention18 stats
01
N95 masks reduce exposure risk by 95% in high-risk occupations
02
Avoid dusty activities during dry windy seasons (Oct-May) in endemic areas
03
Wet soil before digging reduces spore aerosolization by 90%
04
Pregnant women and immunocompromised avoid endemic areas
05
HEPA filters in HVAC systems reduce indoor spores by 99%
06
Annual serologic screening for high-risk workers (e.g., archeologists)
07
Paving or vegetating construction sites cuts cases by 70%
08
Stay indoors during dust storms, close windows, use AC with recirculate
09
No human vaccine available, animal vaccines in development (e.g., dogs)
10
Dust control measures in agriculture reduce farmworker incidence 50%
11
Military personnel in endemic areas: pre/post deployment serology
12
Avoid disturbing soil in endemic zones (AZ, CA, TX, NM)
13
Post-exposure prophylaxis not recommended routinely
14
Diabetes control reduces severe disease risk by 40%
15
Smoking cessation lowers dissemination risk in infected individuals
16
Early antifungal prophylaxis in high-risk post-exposure (e.g., transplant)
17
Public education campaigns reduced unreported cases by 15% in AZ
18
Fencing off construction sites with wind barriers effective
Interpretation
Prevention Interpretation
Prevention is most effective when it combines targeted exposure control and filtration, since N95 masks cut risk by 95% and HEPA HVAC filters can reduce indoor spores by 99%.
More related reading
04 · Category
Prognosis1 stats
01
Annual cost of Valley Fever in AZ exceeds $100 million in medical care
Interpretation
Prognosis Interpretation
From a prognosis standpoint, Valley Fever in Arizona is projected to cost over $100 million each year in medical care, showing a substantial and ongoing burden on patient outcomes and healthcare resources.
05 · Category
Symptoms22 stats
01
Common symptoms include fever (70%), cough (75%), and fatigue (90%) in symptomatic Valley Fever cases
02
Erythema nodosum occurs in 20-30% of primary Valley Fever infections
03
Arthralgias affect 40-50% of patients with acute Valley Fever
04
Chest pain reported in 35% of symptomatic cases
05
Headache occurs in 25% of Valley Fever patients, often mimicking meningitis
06
Dyspnea present in 20% of primary pulmonary coccidioidomycosis cases
07
Weight loss seen in 15-20% of acute cases lasting >1 month
08
Night sweats reported by 40% of symptomatic individuals
09
Rash (maculopapular) in 15-20% of cases
10
Disseminated disease presents with skin lesions in 15-20% of cases
11
Bone/joint pain in 20% of chronic pulmonary cases
12
Meningitis symptoms (severe headache, altered mental status) in 30-50% of CNS-disseminated cases
13
Pericarditis rare, <1% of cases, but can cause chest pain and effusion
14
Lymphadenopathy in 20% of primary infections on chest X-ray
15
Fatigue persists >3 months in 10-15% of cases
16
Myalgias in 50% of acute Valley Fever presentations
17
Sore throat/pharyngitis in 15% of cases
18
Pleural effusion on imaging in 5-10% of primary cases
19
Hilar adenopathy with infiltrates (classic "coin lesion") in 10-20%
20
Chronic fatigue syndrome-like symptoms in 5% post-primary infection
21
Anorexia and malaise in 60% of symptomatic patients
22
Splenic abscess rare, <0.1%, but seen in disseminated disease
Interpretation
Symptoms Interpretation
In symptomatic Valley Fever, fatigue is the standout symptom at 90%, often accompanied by cough at 75% and fever at 70%, while less common but important manifestations like arthralgias in 40 to 50% and chest pain in 35% also broaden the symptom picture.
06 · Category
Treatment20 stats
01
Azoles (fluconazole, itraconazole) are first-line for all forms except mild acute
02
Fluconazole 400mg daily lifelong for coccidioidal meningitis (90% response)
03
Amphotericin B (liposomal 5mg/kg/day) for severe acute or refractory disease
04
Surgical resection for localized pulmonary nodules/cavities in 80% cure rate
05
Itraconazole 200mg BID for chronic pulmonary coccidioidomycosis (70% response)
06
Voriconazole as salvage therapy, response 60% in azole failures
07
Posaconazole effective for osteoarticular disease (71% cure)
08
Mild acute primary infection self-resolves in 90%, no antifungals needed
09
Intrathecal amphotericin for refractory meningitis (shunt reservoir)
10
Relapse rate 25-30% after azole discontinuation in disseminated disease
11
Corticosteroids adjunct for severe pulmonary disease with hypoxia
12
Isavuconazole non-inferior to amphotericin in severe cases (VITAL trial subset)
13
Duration of therapy for bone disease: 12+ months, cure 60-80%
14
Pregnancy: amphotericin B preferred (category B), azoles teratogenic
15
Monitoring LFTs monthly on azoles, hepatotoxicity in 5-10%
16
Therapeutic drug monitoring for itraconazole (target 1-2 mcg/mL)
17
Echinocandins ineffective due to no beta-glucan in spherule wall
18
Shunt placement for hydrocephalus in 40% of meningitis cases
19
Overall mortality 1% for primary, 25-50% for disseminated untreated
20
Vaccine trials (e.g., spherulin-derived) showed 80% efficacy in past, not available
Interpretation
Treatment Interpretation
In the treatment of valley fever, antifungals dominate the approach with azoles as first line for all forms except mild acute, and success rates stay consistently high such as 90 percent response with fluconazole 400 mg daily lifelong for coccidioidal meningitis and 70 percent response with itraconazole 200 mg twice daily for chronic pulmonary disease, while escalation to amphotericin B for severe or refractory cases and voriconazole salvage with 60 percent response in azole failures helps cover the more difficult scenarios.
Reference
Cite This Report
This report is designed to be cited. We maintain stable URLs and versioned verification dates. Copy the format appropriate for your publication below.
APA
Henrik Dahl. (2026, February 13). Valley Fever Statistics. Gitnux. https://gitnux.org/valley-fever-statistics
MLA
Henrik Dahl. "Valley Fever Statistics." Gitnux, 13 Feb 2026, https://gitnux.org/valley-fever-statistics.
Chicago
Henrik Dahl. 2026. "Valley Fever Statistics." Gitnux. https://gitnux.org/valley-fever-statistics.
Sources & references
42 datasets cited across this report · attribution is report-level