International Journal of Biometeorology

, Volume 50, Issue 3, pp 174–182 | Cite as

Climate controls on valley fever incidence in Kern County, California

  • Charles S. ZenderEmail author
  • Jorge Talamantes
Original Article


Coccidiodomycosis (valley fever) is a systemic infection caused by inhalation of airborne spores from Coccidioides immitis, a soil-dwelling fungus found in the southwestern United States, parts of Mexico, and Central and South America. Dust storms help disperse C. immitis so risk factors for valley fever include conditions favorable for fungal growth (moist, warm soil) and for aeolian soil erosion (dry soil and strong winds). Here, we analyze and inter-compare the seasonal and inter-annual behavior of valley fever incidence and climate risk factors for the period 1980–2002 in Kern County, California, the US county with highest reported incidence. We find weak but statistically significant links between disease incidence and antecedent climate conditions. Precipitation anomalies 8 and 20 months antecedent explain only up to 4% of monthly variability in subsequent valley fever incidence during the 23 year period tested. This is consistent with previous studies suggesting that C. immitis tolerates hot, dry periods better than competing soil organisms and, as a result, thrives during wet periods following droughts. Furthermore, the relatively small correlation with climate suggests that the causes of valley fever in Kern County could be largely anthropogenic. Seasonal climate predictors of valley fever in Kern County are similar to, but much weaker than, those in Arizona, where previous studies find precipitation explains up to 75% of incidence. Causes for this discrepancy are not yet understood. Higher resolution temporal and spatial monitoring of soil conditions could improve our understanding of climatic antecedents of severe epidemics.


Climate and health Modeling Valley fever Coccidiodomycosis Coccidiodes immitis 



The authors thank two anonymous reviewers for detailed comments that greatly improved the original manuscript. Discussions with Thomas Larwood and Richard Reynolds improved the quality of this manuscript. Shu Sebesta of the California Department of Health Services provided incidence data. The Valley Fever Center for Excellence provided valuable on-line data. This research was supported in part by NASA Grants NAG5-10147 and NAG5-10546 and by the NCAR Advanced Studies Program.


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Copyright information

© ISB 2005

Authors and Affiliations

  1. 1.Department of Earth System ScienceUniversity of CaliforniaIrvineUSA
  2. 2.Department of Physics and GeologyCalifornia State UniversityBakersfieldUSA

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