<i>Notes From the Field:</i> Coccidioidomycosis Outbreak Among Wildland Firefighters — California, 2021

Abstract

Coccidioidomycosis, also known as Valley fever, is caused by inhalation of spores of the soil-dwelling fungi Coccidioides spp. Although most illness is mild, coccidioidomycosis can cause severe disease resulting in hospitalization or death. On July 28, 2021, the California Department of Forestry and Fire Protection (CAL FIRE) notified the California Department of Public Health (CDPH) of seven wildland firefighters from two crews who had respiratory illness. Crew A (19 members) and crew B (21 members) had worked on wildfires in late June 2021 near the Tehachapi Mountains, a California region with historically high coccidioidomycosis incidence.* Among the seven symptomatic firefighters, three cases of coccidioidomycosis were laboratory-confirmed; two patients developed severe disease. All three firefighters with confirmed coccidioidomycosis reported working in dusty conditions without wearing respiratory protection. Because no vaccine for coccidioidomycosis currently exists, correct use of respiratory protection is important for preventing coccidioidomycosis, especially in regions with high disease incidence.