Coccidioidomycosis among Workers Constructing Solar Power Farms, California, USA, 2011-2014

Abstract

Coccidioidomycosis is associated with soil-disruptive work in Coccidioides-endemic areas of the southwestern United States. Among 3,572 workers constructing 2 solar power-generating facilities in San Luis Obispo County, California, USA, we identified 44 patients with symptom onset during October 2011-April 2014 (attack rate 1.2 cases/100 workers). Of these 44 patients, 20 resided in California outside San Luis Obispo County and 10 resided in another state; 9 were hospitalized (median 3 days), 34 missed work (median 22 days), and 2 had disseminated disease. Of the 25 patients who frequently performed soil-disruptive work, 6 reported frequent use of respiratory protection. As solar farm construction in Coccidioides-endemic areas increases, additional workers will probably be exposed and infected unless awareness is emphasized and effective exposure reduction measures implemented, including limiting dust generation and providing respiratory protection. Medical providers, including those in non-Coccidioides-endemic areas, should suspect coccidioidomycosis in workers with compatible illness and report cases to their local health department.

Keywords: California; Coccidioides; coccidioidomycosis; construction workers; disease transmission; fungi; infectious; occupational health; solar power farms.

Figure 1

Distribution of outbreak cases of coccidioidomycosis among solar farm workers, by month of symptom onset and patients’ residence, San Luis Obispo County, California, USA, October 2011–April 2014. A) Number of cases listed by month of onset and by solar farm. Investigation timeline is displayed below the x-axis. B) Number of cases during this outbreak listed by patient-reported California county or state of permanent residence (gray shading). CDPH, California Department of Public Health; SLOPHD, County of San Luis Obispo Public Health Department.

Figure 2

Flowchart of outbreak investigation of coccidioidomycosis among solar farm workers, San Luis Obispo County, California, USA, October 2011–April 2014. CDPH, California Department of Public Health; SLOPHD, County of San Luis Obispo Public Health Department.

Figure 3

Conditions during solar farm construction in San Luis Obispo County, California, USA. A) Localized dust generation associated with a soil-disruptive activity. Photograph was taken during the week of July 28–August 3, 2013 (courtesy of Aspen Environmental Group). B) Ambient dust exposure because of high-wind conditions. Photo was taken on March 5, 2013 (courtesy of Dennis Shusterman).