While coccidioidomycosis, commonly known as Valley Fever, is primarily endemic to the southwestern United States—particularly Arizona and California—it remains a critical diagnosis for clinicians nationwide to consider. With increasing domestic travel, individuals exposed in endemic areas may present with symptoms far from the source of infection, often leading to delayed or missed diagnoses. Furthermore, the incidence of coccidioidomycosis has risen significantly in recent years, with reported rates in highly affected regions reaching as high as 170 cases per 100,000 people. Because of misdiagnoses, underdiagnoses, and lack of care seeking the CDC estimates that the disease burden is actually much higher, ~206,000- 360,000 cases per year, 10- 18 times more than reported. This growing prevalence underscores the importance of broad clinical awareness, especially when evaluating patients with persistent respiratory symptoms and a travel history to endemic areas.
Coccidioidomycosis is a fungal infection caused by the inhalation of spores from the Coccidioides fungus from an environmental source. Most people who contract the infection will only experience mild symptoms and the infection will self-resolve. However, some will develop severe infections that may require medical care and hospitalization. Coccidioidomycosis is not transmissible from person to person.
Symptoms
About 40% of people affected with coccidioidomycosis develop symptoms and will seek medical treatment about 1 to 3 weeks after exposure. Most patients will present with community-acquired pneumonia (CAP). Typical symptoms include fatigue, cough, dyspnea, headache, night sweat, myalgias, and rash. Approximately 5 to 10% of infected patients have disease progression, develop complications, or develop chronic pulmonary disease. Disseminated disease (involving central nervous system, skin, or bones) occurs in about 1%. Certain populations are at higher risk for dissemination including those with immunocompromised status, HIV, pregnant women and people of African American or Filipino ethnicities.
Diagnosis
Coccidioidomycosis cannot be reliably distinguished from other respiratory illnesses by symptoms alone. 70% of patients receive inappropriate antibiotic therapy because coccidioidomycosis is commonly misdiagnosed. The CDC recommends testing for coccidioidomycosis on the initial presentation of CAP or erythema nodosum following recent respiratory symptoms for patients who:
- Have a link to an outbreak
- Live in or recently traveled to highly endemic or endemic regions
- Have symptoms that have not improved on empiric antibiotics
Additional Resource: CDC Community-Acquired Pneumonia: When to Think Fungus: Coccidioidomycosis Algorithm
Blood tests can determine if your patient has coccidioidomycosis. Serological testing with immunodiffusion (ID) and reflex complement fixation (CF) is the recommended initial testing. Antigen testing and polymerase chain reaction (PCR) testing in the blood or other samples such as cerebrospinal fluid and bronchoalveolar lavage fluid may be available in certain centers and reference laboratories.
Coccidioidomycosis is a nationally notifiable disease and health departments voluntarily submit data to CDC. Click on this CDC link or contact your local health department to understand the reporting procedures in your state.
Treatment
Patients who develop mild symptoms may require supportive care such as rest, hydration, and over the counter pain and fever medications. If symptoms persist or if the patient is at high risk for complications, antifungals may be prescribed See the IDSA Treatment Guidelines for details. Fluconazole is often used for moderate to severe cases; itraconazole is an option for more serious infections. Severe infections that require intravenous medications may be treated with Amphotericin B.
The length of antifungal treatment varies and may be lifelong for the rare cases that lead to meningitis or disseminated disease. Regular follow up and monitoring of disease presence will determine the treatment duration.
References
Centers for Disease Control and Prevention: