| Figure 3. October Temperature and Incidence the following August, Kern County 1989-1998. This graph shows the relationship between valley fever incidence in Kern County, California and temperature during the previous autumn. Although the relationship between the weather and the density of C. immitis in the soil may never be understood in detail, the following relationship seems plausible. During periods of drought, in California for example summer and fall, the number of organisms competing with C. immitis decreases. C. immitis, itself does not thrive, but remains viable though dormant during the arthroconidia phase of its' lifecycle. When the rains return during winter months, the arthroconidia begin to germinate and multiply to higher density than usual because of the lack of competing organisms. Once the soil dries again, the arthroconidia become airborne and potentially infectious. |
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