Valley fever, also known as Coccidioidomycosis, Coccidiosis, Coccidioides immitis infection, or San Joaquin Valley fever is a lung disease caused by the spores of the fungus Coccidioides immitis. The fungus thrives in dusty, arid desert regions such as the the San Joaquin Valley in California, southern Arizona, southern New Mexico, west Texas, and the desert areas of northern Mexico.
The fungus is also found in scattered areas of coastal southern California, southern Nevada, and Utah(1) and is endemic in a few areas in Central and South America, especially in Venezuela
At the time of this writing (Fall 2007), Valley Fever has killed more people worldwide than West Nile Virus or SARS combined. Valley Fever has up to a 50% fatality rate for persons of dark skin and women pregnant in their third trimester.
About 60% of infections do not result in any symptoms and are only recognized later by a positive coccidioidin skin test, which is similar to an allergen skin test.
Mild to Severe Symptoms
However, in 40% of cases, symptoms range from mild to severe. People with a weakened immune system are prone to the more serious infections. Those with AIDS are at an increased risk for lung coccidioidomycosis, as well as for forms of the disease that spread to multiple body systems and skin(2).
The disease will take either an acute, chronic, or disseminated form. Acute pulmonary coccidioidomycosis is nearly always mild, with few or no symptoms, and resolves without treatment. The incubation period is 7 to 21 days.
Acute coccidioidomycosis is rare. Roughly 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.
Infected lung abscesses can form and rupture, releasing pus into the pleural space between the lungs and ribs. This condition is even less common than the acute form.
In disseminated disease, spread of infection to the bones, lungs, liver, meninges, brain, skin, heart, and pericardium around the heart may take place. Meningitis occurs in 30-50% of cases of disseminated disease. The course of the disease may be rapid for immunosuppressed patients.
Any or all of the following can be common symptoms:
Mild cases of coccidioidomycosis usually clear up on their own, without treatment. For severe cases, antifungal medications are required(3). Disseminated coccidioidomycosis is fatal if untreated, but death may also occur in some patients even when medical treatment is received. Your best bet for preventing exposures to C. immitis spores is to avoid situations where soil that might be contaminated can be inhaled. If in doubt, wear a protective mask.
1. Kamel SM, Wheat LJ, Garten ML, Bartlett MS, Tansey MR, Tewari RP. Production and characterization of murine monoclonal antibodies to Histoplasma capsulatum yeast cell antigens. Infect Immun 1989;57:896-901.
2. Bronnimann DA, Adam RD, Galgiani JN, Habib MP, Peterson EA, Porter B, et al. Coccidioidomycosis in the acquired immunodeficiency syndrome. Ann Intern Med 1987;106:372-9.
3. Catanzaro A, Fierer J, Friedman PJ. Fluconazole in the treatment of persistent coccidioidomycosis. Chest 1990;97:666-9.
This article is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the disease described above or think that you may have this infection, consult a health care provider.