C. immitis arthroconidia occur sporadically, but not uncommonly, in dust derived from soils of the southwest United States as well as parts of Central and South America. It is the etiological agent of coccidioidomycosis and grows in the upper (5 - 20 cm) horizons of soils in endemic areas. Endemic areas generally are arid to semiarid with rainfall of 12 to 50 cm, mild winters, and long hot seasons. Arizona endemic soils are classified as hyperthermic arid, thermic arid and semiarid, having mean annual soil temperatures from 15 to over 22°C and receiving annual precipitation from <25 to 41cm. The saprophytic phase is characterized by branching segmented hyphae that form a network of mycelium. At maturity, arthroconidia, 2 to 5um in size, are formed as barrel shaped, rectangular segments of the hyphae that can be separated by soil disturbance and dispersed by wind. Airborne arthroconidia inhaled by an appropriate host may cause primary infection and the parasitic phase of the C. immitis lifecycle is initiated.
A habitat suitability index of C. immitis has been modeled in Organ Pipe Cactus National Monument, Arizona using a spatial fuzzy system. This model predicts the favorableness of given soils for the growth of C. immitis. The fuzzy system can be used to model the effect of climatic fluctuation on the distribution of C. immitis in Arizona and elsewhere. When combined with USGS dust monitoring efforts in the southwest United States, the fuzzy system has the potential of being a tool for coccidioidomycosis mitigation.
Learning Objectives: At the conclusion of the session, the participant in this session will be able to: 1) Articulate a procedure for assessing the habitat suitability index of C. immitis; 2) Discuss how it may be possible to model changes in C. immitis habitat due to global climatic change; 3) Discuss how knowledge of C. immitis habitat may contribute to coccidioidomycosis mitigation.
Keywords: Environment, Emerging Diseases
Presenting author's disclosure statement:
Organization/institution whose products or services will be discussed: None
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.