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USING SSURGO TO MAP SPATIAL AND TEMPORAL DISTRIBUTIONS ROBERT R. DOBOS NSSC, LINCOLN NE 18 NOVEMBER 2014 Valley Fever Habitat Model
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What is “Valley Fever”? Valley Fever (Coccidioidomycosis) is a disease caused by the soil borne fungi Coccidioides immitis or Coccidioides posadasii Also known as "California fever", "desert rheumatism", and "San Joaquin Valley fever“ The disease is endemic to the southwestern United States and other regions of similar climate in the western hemisphere.
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Distribution
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Significance
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Risk Factors Anyone can get valley fever by inhaling airborne spores in endemic areas. Older adults, particularly those ages 60 and older Valley fever cannot spread from person to person Some groups of people are more at risk: Military personnel Workers in dusty environments Some groups of people are at increased risk for developing more severe forms of valley fever, including African Americans, Asians, women in their third trimester of pregnancy, and people with weak immune systems.
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Life Cycle Characteristics Saprophytic stage lives in the soil as mycelia and hyphae Mature hyphae produce arthroconidia, 1.5 to 4.5 microns wide, 5 to 30 microns long Arthroconidia move in the wind, until Inhaled by a mammal, the arthroconidia change into spherules which mature and burst, releasing endospores which grow into new spherules
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Temporal Distribution of Cases, non-Xeric
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Temporal Distribution of Cases, Xeric
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Symptoms For most people: fever, cough, headache, rash, muscle aches, or joint pain similar to other common illnesses, diagnosis and treatment are often delayed Symptoms can last from weeks to months In a very small proportion of people (2 to 4 %): The infection can cause chronic pneumonia, spread from the lungs to the rest of the body (disseminated) and cause meningitis (brain or spine infection) or even death.
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Saprophyte Habitat “Lower Sonoran Life Zone” 200 to 300 mm rain annually 10.5 to 23.3 degrees C mean annual air temperature Soil organic matter Soluble salts Xeric – C. immitis Non-Xeric – C. posadasii
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Objective Use SSURGO data to produce a model for predicting the distribution of the saprophytic stage of Coccidioides spp Use SSURGO to produce mapping at a fine resolution to be able to target areas for dust control
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Model Parameters Optimal mean annual air temperature of 16 C – xeric 19 C – non-xeric Optimal mean annual precipitation 350 mm xeric 200 mm non-xeric Optimal Heat loading South aspect Low albedo Moderate slope Optimal Soluble salts Soil electrical conductivity of over 4 dS/m pH over 8.0 Presence of gypsum SAR greater than 50 Organic matter 6kg/m 2 Water retention difference 11% (vol/vol) Slope shape gathers water and spores
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Parameters in NASIS
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Result
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Compared to Another Model
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Impose 2C Warming
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