Abstract and Introduction
Abstract
Community-acquired pneumonia (CAP) often results in severe illness and death. In large, geographically defined areas where Coccidioides spp. are endemic, coccidioidomycosis is a recognized cause of CAP, but its frequency has not been studied extensively. To determine the frequency of patients with coccidioidomycosis, we conducted a prospective evaluation of 59 patients with CAP in the Phoenix, Arizona, area. Of 35 for whom paired coccidioidal serologic testing was performed, 6 (17%) had evidence of acute coccidioidomycosis. Coccidioidal pneumonia was more likely than noncoccidioidal CAP to produce rash. The following were not found to be risk factors or reliable predictors of infection: demographic features, underlying medical conditions, duration of time spent in disease-endemic areas, occupational and recreational activities, initial laboratory studies, and chest radiography findings. Coccidioidomycosis is a common cause of CAP in our patient population. In the absence of distinguishing clinical features, coccidioidal pneumonia can be identified only with appropriate laboratory studies.
Introduction
Coccidioidomycosis is caused by infection with Coccidioides spp., which consist of the nearly identical Coccidioides immitis and C. posadasii that grow in the soils of the desert southwestern United States and in limited areas of Central and South America. When soil is disrupted, airborne arthroconidia can be inhaled, causing infections in humans and animals. These infections can be asymptomatic or can produce illness of varying severity, from mild, self-limited respiratory infection to severe, life-threatening pneumonia. In a small percentage of patients, Coccidioides spp. may spread beyond the pulmonary tract, most frequently to the cutaneous, osteoarticular, or central nervous systems.
The incidence of coccidioidomycosis has increased dramatically from 2.5 cases/100,000 persons in 1996 to 8.4 cases/100,000 persons in 2006 in California and from 21 cases/100,000 in 1997 to 91 cases/100,000 in 2006 in Arizona. Clinicians in disease-endemic areas are usually aware of coccidioidomycosis but often do not consider the diagnosis in patients who initially have respiratory symptoms. A possible explanation for this oversight may be uncertainty about the frequency of coccidioidomycosis as a cause of acute community-acquired pneumonia (CAP). Valdivia et al. reported that 29% of patients with CAP in Tucson, Arizona, had coccidioidomycosis. To determine the frequency of coccidioidal pneumonia in a second sample of the population, we studied patients with CAP in the Phoenix, Arizona, metropolitan area.