Coccidioides immitis arthroconidia as would be observed in soil.
Coccidioides immitis spherules as would be observed in tissues.
Geographic distribution of coccidioidomycosis (Valley Fever). Figure from Valley Fever Center for Excellence
Coccidioidomycosis, commonly known as Valley Fever, Desert Rheumatism, Golfers Lung, is a serious disease caused by inhaling spores of Coccidioides immitis or Coccidioides podasii. Coccidioides grows in soil in dry, desert areas of the western United States from Washington to Texas. In particular, most of Arizona and the central valley of California are highly endemic. The spores are spread in dust raised from storms, haboobs, earthquakes, construction, agriculture, digging, off-road vehicles, and any other contact with disturbed, infected soil. While anyone living in, working in, visiting, or traveling through endemic regions is at risk, people in high risk occupations, new to an endemic region, immune suppressed, elderly, children, or pregnant women have been observed to be at higher risk of infection.
Historically, 30-60% of the people living in the endemic regions have demonstrated skin test reactivity to Coccidioides.
Many people, about 60%, who are infected remain relatively asymptomatic and recover without long-term problems. These people historically maintain lifelong immunity to Coccidioides unless they experience immune suppression or very high dose exposures.
Another 40% of cases will be symptomatic forms that result in flu-like symptoms, primarily developing pulmonary disease. Symptoms may include fatigue, cough, chest pain, fever, night sweats, rash, headache, and joint aches. Some patients may develop painful red to brown rashes or bumps on their legs or elsewhere (i.e., erythema nodosum). It is important that symptomatic cases are evaluated by a physician, and that Valley Fever be part of a differential diagnosis for pulmonary infections in endemic regions. Even moderate cases can require months of treatment and may result in weeks of missed school or work. About 40% of symptomatic cases will require hospitalization during the course of disease. Patients may experience symptoms, in particular lethargy, for a sustained period after recovering from pulmonary infections. Remission is not uncommon after treatment has been discontinued.
In about 1-2% of infections, the disease disseminates. The most common site of spread is in the skin, but Coccidioides may spread to bone, joints, or most other soft tissues. An extremely serious form of disseminated disease is spread to the central nervous system. Disseminated disease can occur months to years after the initial pulmonary infection often, though not always, associated with concurrent disease, surgery, or trauma. While anyone with less severe forms of coccidioidomycosis may develop the disseminated form of the disease, African-Americans, Filipinos, and people with suppressed immune systems are at a greater risk for disseminated disease.
Coccidioidomycosis is diagnosed by physicians based on the history including geography, signs and symptoms, isolation or staining of Coccidioides in biopsies, sputum or lavage fluids, and serological testing. Typically a battery of serological tests are used initially and are then repeated to observe changes in the serological markers over time. Like skin testing, serological tests may not be diagnostic during acute or disseminated forms of coccidioidomycosis or in individuals with compromised immune function. Additionally, serological markers may not be able to identify individuals with prior exposure and immunity to Coccidioides. Repeated serological testing may be required to diagnose coccidioidomycosis and not all patients will demonstrate antibodies to Coccidioides.
Treatment of coccidioidomycosis is both costly and long term. Not all cases require antifungal treatment. Depending upon the course of the disease and risk factors for serious or disseminated disease, treatment may involve oral antifungals such as fluconazole, itraconazole, and posiconazole. Even moderate cases require many weeks or months of treatment. In the case of severe or disseminated disease, physicians may administer antifungals intravenously or even directly into the spinal fluid. Disseminated disease often requires lifetime antifungal treatment.
Long-term consequences may include the formation of cavities or nodules in the chest or fungal abscesses. Such cavities have been found in people with unknown history of coccidioidomycosis and can be misdiagnosed as lung cancer. Additionally, long term consequences of infections involving the central nervous system may lead to lifetime disabilities.
For more information on coccidioidomycosis or Valley Fever, the following resources are available:
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