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Determining Geological/Ecological Occurrence Models for Coccidioides Immitis

Valley fever Coccidioides immitis (C. immitis) is an emerging infectious, inhalation disease endemic to arid lands of the southwestern U.S., from the coast of southern California to central Texas. Within this endemic region, growth sites range in size from several tens of square meters to several square kilometers. Although some sites have been identified, their distributions are poorly known throughout the entire endemic area and their recognition is difficult; moreover, the apparent failure of C. immitis to colonize outside of the specific sites has not been adequately explained. While many critical habitat parameters are known, the necessary and sufficient conditions for the occurrence of C. immitis in soils are not known. Conditions that promote C. immitis growth may be estimated through chemical and biological analysis of soils, analysis of epidemiological, canine epidemiological, climatic and geomorphologic data, remote sensing interpretation, and spatial modeling. The habitat parameters can then be used to define and predict regions of C. immitis infestation in soils.

This investigation determines the properties of soils that contain C. immitis and models the habitat of this fungus that is responsible for Valley Fever. The investigation works collaboratively with University of Arizona researchers and other medical institutions, whose objectives include understanding the climatic controls of C. immitis in soils, coccidioidomycosis epidemiological relationships with soils, soil disturbances, in-situ C. immitis determination, climates that promote C. immitis growth, and spatial modeling. We will produce maps showing the favorableness for occurrence of C. immitis.