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Coccidioides

Coccidioidomycosis also known as valley fever, is an infection caused by inhalation of Coccidioides immitis/posadasii arthroconidia (spores). Coccidioides is a soil-dwelling fungus that is endemic to arid regions of Mexico, Central and South America, and the southwestern United States. Arizona’s Sonoran Desert, which includes the metropolitan areas of Phoenix and Tucson, and California’s southern San Joaquin Valley are particularly high-risk areas and account for 95% of cases. Coccidioides also occurs to a lesser extent in Nevada, New Mexico, Utah, and Texas.

Approximately 40% of infected persons develop symptoms similar to community acquired pneumonia caused by bacteria. In endemic areas, Coccidioides has been determined to be responsible for 15-30% of cases of community acquired pneumonia. These symptoms occur after a 1 to 3 week incubation period and include fatigue, cough, fever, shortness of breath, and headache. A small proportion of patients develop life-severe or chronic pulmonary disease. Less than 1% develop disseminated disease that can lead to chronic sequelae requiring lifelong treatment. Risk factors include immunosuppression, black race, and Filipino ethnicity.

Serologic testing for coccidioidomycosis should be considered when patients exhibit symptoms of pulmonary or meningeal infection and have lived or traveled in areas where Coccidioides immitis/posadasii is endemic. An enzyme immunoassay detects total antibody (IgG and IgM) to complement fixing and tube precipitin antigens.A positive result is presumptive evidence that the patient was previously or is currently infected with Coccidioides immitis/posadasii.A negative result indicates the absence of antibodies to Coccidioides immitis/posadasii and is presumptive evidence that the patient has not been previously exposed to and is not infected with Coccidioides.

False negative results may occur if is a specimen is collected during early acute infection or in patients with immunosuppression. If infection is suspected, another specimen should be drawn in 7 to 14 days.

References

Galgiani JN, Ampel NM, Blair JE, et al. Infectious Diseases Society of America (IDSA) clinical practice guideline for the treatment of coccidioidomycosis. Clin Infect Dis 2016;2016:27.

Benedict K, McCotter OZ, Brady S, et al. Surveillance for Coccidioidomycosis — United States, 2011–2017. MMWR Surveill Summ 2019;68(No. SS-7):1–15.

Kuberski T, Herrig J, Pappagianis D. False-positive IgM serology in coccidioidomycosis. J Clin Microbiol 2010;48:2047–9.

Chang DC, Anderson S, Wannemuehler K, et al. Testing for coccidioidomycosis among patients with community-acquired pneumonia. Emerg Infect Dis 2008;14:1053–9.

Rosenstein NE, Emery KW, Werner SB, et al. Risk factors for severe pulmonary and disseminated coccidioidomycosis: Kern County, California, 1995–1996. Clin Infect Dis 2001;32:708–15.

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