Also called valley fever and San Joaquin Valley fever, coccidioidomycosis is a fungal infection. It occurs primarily as a respiratory infection, although generalized dissemination may occur. The primary pulmonary form usually is self-limiting and seldom fatal. The rare secondary (progressive, disseminated) form produces abscesses throughout the body and carries a mortality of up to 60%, even with treatment.
Such dissemination is more common in darkskinned men and pregnant women. Immunosuppressive conditions, especially human immunodeficiency virus infection, Hodgkin's disease, and malignant lymphoma, also are risk factors for disseminated disease.
Coccidioidomycosis is endemic to the southwestern United States, especially between the San Joaquin Valley in California and southwestern Texas. It's also found in Mexico and central and South America.
Because of population distribution and an occupational link (it's common in migrant farm laborers), coccidioidomycosis strikes many Philippine Americans, Mexican Americans, Native Americans, and Blacks. In primary infection, the incubation period ranges from 1 to 4 weeks.
The infection is caused by breathing in the spores of a fungus found in desert regions such as Arizona or California's San Joaquin Valley. The disease can have an acute, chronic, or disseminated form.
The chronic form usually develops after a period of months to years following a harmless infection that may have gone undiagnosed. Lung abscesses may form and may rupture into the pleural spaces causing empyema or bronchopleural fistula. Scarring (fibrosis) and cavities may gradually form in the upper lungs as the chronic form of coccidioidomycosis slowly progresses over months to years.
Still, the majority of pulmonary coccidioidomycosis infections do not become chronic. In fact, the majority of infections cause no symptoms and are only recognized by a positive coccidioidin skin test.
Dark-skinned people and people with a weak immune system are more susceptible to infection and more likely to form chronic or disseminated forms of the disease.
Symptoms and Signs
Additional symptoms that may be associated with this disease:
Sputum, urine, and pus should be examined for C. immitis by wet smear and culture. The mold form must be handled with care as it can infect laboratory personnel. Serologic tests are also helpful in the diagnosis.
The primary form - and sometimes the disseminated form - produces a positive coccidioidin skin test. In the first week of illness, complement fixation for immunoglobulin G antibodies, or in the first month, positive serum precipitins (immunoglobulins) also establish the diagnosis. Examination or immunodiffusion testing of sputum, pus from lesions, and a tissue biopsy may show C. immitis spores. Antibodies in pleural and joint fluid and an increasing serum or body fluid antibody titer indicate dissemination.
Mild primary coccidioidomycosis usually requires only rest and relief of symptoms. Severe primary disease and dissemination require I. V. amphotericin B. Patients with more indolent disseminated infection are given ketoconazole, itraconazole, or fluconazole.
CNS dissemination is usually treated with fluconazole but may require intrathecal administration of amphotericin B. Severe pulmonary lesions may require lobectomy in addition to chemotherapy if the infection is confined to one lung.
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