Detection and monitoring of Coccidioides spp. in the environment
Valley fever or coccidioidomycosis is a life-threatening fungal infection caused by inhalation of arthroconidia (airborne particles) of the two closely related species, Coccidioides immitis and C. posadasii, present in soil and dust of desert areas in South, Central and North America. Unlike most other human pathogenic fungi, Coccidioides spp. can infect immunocompetent individuals and cause a broad spectrum of diseases ranging from asymptomatic infection to mild respiratory illness to severe life-threatening infections. The total number of infections remains unknown: in the United States, over 10,000 of human cases are reported each year and the actual burden of the disease is estimated to be close to 100,000 cases per year. The disease is also prevalent in Mexico and has been reported in Argentina, Bolivia, Brazil, Guatemala, Panama and Paraguay. Recent data suggest that the incidence of valley fever is increasing and the pathogen’s endemic range is expanding. For example, in Arizona, the reported incidence of valley fever has risen by 900% in the past decade. Furthermore, in the United States, clusters of valley fever and viable arthroconidia of C. immitis in the environment have been reported in the southeast of Washington State, well outside of the currently accepted endemic range. Although the exact causes of the increased incidence and the expanding geographic range of coccidioidomycosis are unknown, climate and population changes which have occurred in recent decades have likely contributed to these trends.
To better understand the distribution and spread of Coccidioides sp. in the environment and to develop measures to prevent human exposure, we have developed several methods for detection and monitoring of these pathogens in soil and air samples. This presentation discusses our recent findings, describing the distribution of Coccidioides sp. in the US.