Coccidioidomycosis : Overview, Causes, & Risk Factors

Alternate Names : San Joaquin Valley fever, Valley fever

Definition

Coccidioidomycosis is infection with the spores of the fungus Coccidioides immitis.

Overview, Causes, & Risk Factors

Infection is caused by inhaling the spores of the fungus Coccidioides immitis. This fungus is often found in desert regions. About 60% of infections cause no symptoms and are only recognized later by a positive coccidioidin skin test.

In the remaining 40% of cases, symptoms range from mild to severe. People with a compromised immune system tend to have more serious infections. Individuals with AIDS are at higher risk for lung (pulmonary) coccidioidomycosis, as well as for the disseminated (spread to many organs) and skin (cutaneous) forms of the disease.

The disease can have an acute, chronic, or disseminated form. Acute pulmonary coccidioidomycosis is almost always mild, with few or no symptoms, and goes away without treatment. The incubation period — the time between breathing in the spores and becoming sick — is 7 to 21 days.

Acute coccidioidomycosis is uncommon. In any given year, about 3% of people who live in an area where coccidiomycosis is commonly seen will develop the disease.

Chronic pulmonary coccidioidomycosis can develop 20 or more years after initial infection, which may not have been recognized, diagnosed, or treated at the time. Infections (lung abscesses) can form and rupture, releasing pus (empyema) between the lungs and ribs (pleural space). This disorder is even less common than the acute form.

In disseminated disease, infection may spread to the bones, lungs, liver, lining covering the brain and spinal cord (meninges), brain, skin, heart, and the sac around the heart (pericardium). Meningitis occurs in 30-50% of cases of disseminated disease. The disease may get worse quickly in immunosuppressed people.

Pictures & Images

Coccidioidomycosis – chest x-ray

This chest x-ray shows the affects of a fungal infection, coccidioidomycosis. In the middle of the left lung (seen on the right side of the picture) there are multiple, thin-walled cavities (seen as light areas) with a diameter of 2 to 4 centimeters. To the side of these light areas are patchy light areas with irregular and poorly defined borders.

Pulmonary nodule – front view chest x-ray

Pulmonary nodule - front view chest x-ray

This x-ray shows a single lesion (pulmonary nodule) in the upper right lung (seen as a light area on the left side of the picture). The nodule has distinct borders (well-defined) and is uniform in density. Tuberculosis (TB) and other diseases can cause this type of lesion.


Review Date : 12/3/2008
Reviewed By : David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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