Statistical modeling of valley fever data in Kern County, California

  • Jorge TalamantesEmail author
  • Sam Behseta
  • Charles S. Zender
Original Article


Coccidioidomycosis (valley fever) is a fungal infection found in the southwestern US, northern Mexico, and some places in Central and South America. The fungus that causes it (Coccidioides immitis) is normally soil-dwelling but, if disturbed, becomes air-borne and infects the host when its spores are inhaled. It is thus natural to surmise that weather conditions that foster the growth and dispersal of the fungus must have an effect on the number of cases in the endemic areas. We present here an attempt at the modeling of valley fever incidence in Kern County, California, by the implementation of a generalized auto regressive moving average (GARMA) model. We show that the number of valley fever cases can be predicted mainly by considering only the previous history of incidence rates in the county. The inclusion of weather-related time sequences improves the model only to a relatively minor extent. This suggests that fluctuations of incidence rates (about a seasonally varying background value) are related to biological and/or anthropogenic reasons, and not so much to weather anomalies.


GARMA modeling Time-series analysis Valley fever prediction Coccidioidomycosis Coccidioides immitis 



Thanks are due to Emma Chaput of the Kern County Department of Public Health for providing us with the weekly incidence data, and to Francisco Beltran of the CSUB Mathematics Department for assisting us with some of the computer programming. We are immensely thankful to Thomas Larwood, M.D., and to Kirt Emery, M.P.H., of the Kern County Department of Public Health for important discussions regarding this work. Finally, we thank the anonymous referees for their careful suggestions. Their comments helped us to improve the manuscript considerably both in readability as well as content.


  1. Akaike H (1974) A new look at the statistical model identification. IEEE Trans Automatic Control 19(6):716–723CrossRefGoogle Scholar
  2. Benjamin MA, Rigby RA, Stasinopoulos DM (2003) Generalized autoregressive moving average models. J Am Stat Assoc 98:214–223CrossRefGoogle Scholar
  3. Box GP, Jenkins GM, Reinsel GC (1994) Time series analysis, 3rd edn. Prentice-Hall, Englewood Cliffs, NJGoogle Scholar
  4. Breslow NE (1984) Extra-Poisson variation in log-linear models. Appli Statist 33:38–44CrossRefGoogle Scholar
  5. Centers for Disease Control and Prevention (1993) Coccidioidomycosis - United States, 1991–1992. Morb Mortal Wkly Rep 42:21–24Google Scholar
  6. Centers for Disease Control and Prevention (1994) Update: coccidioidomycosis - California 1991–1993. Morb Mortal Wkly Rep 43:421–423Google Scholar
  7. Centers for Disease Control and Prevention (1996) Coccidioidomycosis - Arizona 1990–1995. Morb Mortal Wkly Rep 45:1069–1073Google Scholar
  8. Centers for Disease Control and Prevention (2003) Increase in coccidioidomycosis - Arizona, 1998–2001. Morb Mortal Wkly Rep 52:109–112Google Scholar
  9. Emery K (2006) private communicationGoogle Scholar
  10. Hugenholtz PG (1957) Climate and coccidioidomycosis. In: Proc Symp Coccidioidomycosis, Phoenix, Arizona. Public Health Service, Washington, DC, pp 136–143Google Scholar
  11. Jinadu BA (1995) Valley Fever Task Force report on the control of Coccidioides immitis. Technical Report, Kern County Health Department, Bakersfield, CaliforniaGoogle Scholar
  12. Kedem B, Fokianos K (2002) Regression models for time series analysis. Wiley, New YorkCrossRefGoogle Scholar
  13. Kirkland TN, Fierer J (1996) Coccidioidomycosis: a reemerging infectious disease. Emerg Infect Dis 3:192–199CrossRefGoogle Scholar
  14. Kolivras KM, Comrie AC (2003) Modeling valley fever (coccidioidomycosis) incidence on the basis of climate conditions. Int J Biometeorol 47:87–101PubMedGoogle Scholar
  15. Kolivras KM, Johnson PS, Comrie AC, Yool SR (2001) Environmental variability and coccidioidomycosis (valley fever). Aerobiologia 17:31–42CrossRefGoogle Scholar
  16. Larwood T (2003) private communicationGoogle Scholar
  17. Larwood T, Emery K (2005) private communicationGoogle Scholar
  18. Lee RV (1944) Coccidioidomycosis in the Western Flying Training Command. CA & Western Med 61:133–134Google Scholar
  19. Maddy KT (1957) Ecological factors possibly relating to the geographic distribution of Coccidioides immitis. In: Proc Symp Coccidioidomycosis, Phoenix, Arizona. Public Health Service, Washington, DC, pp 144–157Google Scholar
  20. Nelder JA, Wedderburn RWM (1972) Generalized linear models. Wiley, New YorkGoogle Scholar
  21. Pappagianis D (1988) Epidemiology of coccidioidomycosis. In: McGinnins M (ed) Current topics in mycology, vol 2. Springer, Berlin Heidelberg New York, pp 199–238Google Scholar
  22. Pappagianis D (1994) Marked increase in cases of coccidioidomycosis in California:1991, 1992, and 1993. Clin Infect Dis 19(Suppl 1):S14–S18PubMedGoogle Scholar
  23. Pappagianis D, Einstein H (1978) Tempest from Tehachapi takes toll or Coccidioides conveyed aloft and afar. West J Med 129:527–530PubMedGoogle Scholar
  24. Schneider E, Hajjeh RA, Spiegel RA, Jibson RW, Harp EL, Marshall GA, Gunn RA, McNeil MN, Pinner RW, Baron RC, Burger RC, Hutwagner LC, Crump C, Kaufman L, Reef SE, Feldman GM, Pappagianis D, Werner SB (1997) A coccidioidomycosis outbreak following the Northridge, Calif, Earthquake. JAMA 277:904–908PubMedCrossRefGoogle Scholar
  25. Smith CE, Beard RR, Rosenberger HG, Whiting EG (1946) Effect of season and dust control on coccidioidomycosis. JAMA 132:833–838Google Scholar
  26. Venables WN, Ripley BD (1997) Modern applied statistics with S-Plus, 2nd edn. Springer, Berlin Heidelberg New YorkGoogle Scholar
  27. Zender CS, Talamantes J (2006) Climate controls on valley fever incidence in Kern County, California. Int J Biometeorol 50:174–182PubMedCrossRefGoogle Scholar

Copyright information

© ISB 2006

Authors and Affiliations

  • Jorge Talamantes
    • 1
    Email author
  • Sam Behseta
    • 2
  • Charles S. Zender
    • 3
  1. 1.Department of Physics and GeologyCalifornia State UniversityBakersfieldUSA
  2. 2.Department of MathematicsCalifornia State UniversityBakersfieldUSA
  3. 3.Department of Earth System ScienceUniversity of CaliforniaIrvineUSA

Personalised recommendations