Occupational coccidioidomycosis in California: outbreak investigation, respirator recommendations, and surveillance findings.

Objective: To describe the investigation of a 2007 occupational coccidioidomycosis outbreak in California, recommend prevention measures, and assess statewide disease burden. Methods: We evaluated the worksite, observed work practices, interviewed the workers and employer, reviewed medical records, provided prevention recommendations including risk-based respirator selection, and analyzed statewide workers' compensation claims. Results: Ten of 12 workers developed acute pulmonary coccidioidomycosis; none used respiratory protection. We recommended engineering, work practice, and administrative controls, powered air-purifying respirator use, and medical care. Occupational coccidioidomycosis incidence nearly quadrupled in California from 2000 to 2006, with the highest rates in construction and agricultural workers. Conclusions: Construction workers are at risk for occupational coccidioidomycosis. The high attack rate in this outbreak was due to lack of awareness, rainfall patterns, soil disruption, and failure to use appropriate controls. Multiple risk-based measures are needed to control occupational coccidioidomycosis in endemic areas.