Distance from construction site and risk for coccidioidomycosis, Arizona, USA

Coccidioides spp. fungi, which are present in soil in the southwestern United States, can become airborne when the soil is disrupted, and humans who inhale the spores can become infected. In 2012, our institution in Maricopa County, Arizona, USA, began a building project requiring extensive excavation of soil. One year after construction began, we compared the acquisition of coccidioidomycosis in employees working adjacent to the construction site (campus A) with that of employees working 13 miles away (campus B). Initial testing indicated prior occult coccidioidal infection in 20 (11.4%) of 176 campus A employees and in 19 (13.6%) of 140 campus B employees (p = 0.55). At the 1-year followup, 3 (2.5%) of 120 employees from campus A and 8 (8.9%) of 90 from campus B had flow cytometric evidence of new coccidioidal infection (p = 0.04). The rate of coccidioidal acquisition differed significantly between campuses, but was not higher on the campus with construction.