Skip directly to page options Skip directly to A-Z link
Volume 17, Number 8—August 2011
Research

Early Warning System for West Nile Virus Risk Areas, California, USA

Ryan M. Carney1Comments to Author , Sean C. Ahearn, Alan McConchie2, Carol A. Glaser, Cynthia Jean, Chris Barker, Bborie Park, Kerry Padgett, Erin Parker, Ervic Aquino, and Vicki L. Kramer
Author affiliations: Author affiliations: California Department of Public Health, Richmond, California, USA (R.M. Carney, C. Glaser, C. Jean, K. Padgett, E. Parker, E. Aquino); City University of New York, New York, New York, USA (S.C. Ahearn, A. McConchie); University of California, Davis, California, USA (C. Barker, B. Park); California Department of Public Health, Sacramento, California, USA (V. Kramer)

Main Article

Figure 2

Schematic of the Dynamic Continuous-Area Space-Time (DYCAST) procedure, illustrating domains of Knox test (16,17) implemented at the center of an individual ≈0.44 km2 grid cell. The 2.4-km (1.5-mi) radius of the spatial domain represents twice the daily feeding distance (14) of Culex spp. mosquitoes in California (18) and is equivalent to the effective flight range of these vectors (19,20). The 21-day temporal domain accounts for the extrinsic incubation period of West Nile virus (21) and 2 avia

Figure 2. Schematic of the Dynamic Continuous-Area Space-Time (DYCAST) procedure, illustrating domains of Knox test (16,17) implemented at the center of an individual ≈0.44 km2 grid cell. The 2.4-km (1.5-mi) radius of the spatial domain represents twice the daily feeding distance (14) of Culex spp. mosquitoes in California (18) and is equivalent to the effective flight range of these vectors (19,20). The 21-day temporal domain accounts for the extrinsic incubation period of West Nile virus (21) and 2 avian infection cycles of 7 days each (5,14,22). These bounds define the spatiotemporal domain, within which reports of dead birds (asterisks) are evaluated for proximity in space (0.40 km) and time (3 days) (small white cylinder). Statistical significance of dead bird report pairing is assessed by using random simulations (p<0.1) (15). Procedure is repeated at other cell centers to create a continuous surface of risk.

Download

Main Article

References
  1. Centers for Disease Control and Prevention. Surveillance for human West Nile virus disease—United States, 1999–2008. Surveillance Summaries. MMWR Morb Mortal Wkly Rep. 2010;59:SS–2 [cited 2010 Apr 2]. http://www.cdc.gov/mmwr/pdf/ss/ss5902.pdf
  2. California Department of Health Services. Vector-borne diseases in California, 2003: annual report. Sacramento (CA): The Department. 2004 Aug [cited 2011 Feb 28]. http://www.cdph.ca.gov/programs/vbds/Documents/VBDSAnnualReport03.pdf
  3. California Department of Public Health. Human West Nile virus activity, California, 2004–2010. Updated 2010 Sep 3. Sacramento (CA): The Department; 2010 [cited 2010 Sep 05]. http://westnile.ca.gov/downloads.php?download_id=1792&filename=2004-2010_WNV_Case_Summary-13.pdf
  4. Turell  MJ, Sardelis  MR, Dohm  DJ, O’Guinn  ML. Potential North American vectors of West Nile virus. Ann N Y Acad Sci. 2001;951:317–24. DOIPubMedGoogle Scholar
  5. Komar  N, Langevin  S, Hinten  S, Nemeth  N, Edwards  E, Hettier  D, Experimental infection of North American birds with the New York 1999 strain of West Nile virus. Emerg Infect Dis. 2003;9:311–22.PubMedGoogle Scholar
  6. Wheeler  SS, Barker  CM, Fang  Y, Armijos  MV, Carroll  BD, Husted  S, Differential impact of West Nile virus on California birds. Condor. 2009;111:1–20. DOIPubMedGoogle Scholar
  7. McCaughey  K, Miles  SQ, Woods  L, Chiles  RE, Hom  A, Kramer  VL, The California West Nile virus dead bird surveillance program. Proceedings of the Mosquito and Vector Control Association of California. 2003;71:38–43.
  8. California Department of Public Health, Mosquito and Vector Control Association of California, University of California. California mosquito-borne virus surveillance and response plan. Sacramento (CA): The Department. Vector-Borne Disease Section. 2009 Apr [cited 2011 Feb 28]. http://www.cdph.ca.gov/HealthInfo/discond/Documents/2009MosqSurvRespPlan.pdf
  9. Eidson  M, Schmit  K, Hagiwara  Y, Anand  M, Backenson  PB, Gotham  I, Dead crow densities and human cases of West Nile virus, New York State, 2000. Emerg Infect Dis. 2001;7:662–4. DOIPubMedGoogle Scholar
  10. Eidson  M, Schmit  K, Hagiwara  Y, Anand  M, Backenson  PB, Gotham  I, Dead crow density and West Nile virus monitoring, New York. Emerg Infect Dis. 2005;11:1370–5.PubMedGoogle Scholar
  11. Johnson  GD, Eidson  M, Schmit  K, Ellis  A, Kulldorff  M. Geographic prediction of human onset of West Nile virus using dead crow clusters: an evaluation of year 2002 data in New York State. Am J Epidemiol. 2006;163:171–80. DOIPubMedGoogle Scholar
  12. Mostashari  F, Kulldorff  M, Hartman  JJ, Miller  JR, Kulasekera  V. Dead bird clusters as an early warning system for West Nile virus activity. Emerg Infect Dis. 2003;9:641–6.PubMedGoogle Scholar
  13. Watson  JT, Jones  RC, Gibbs  K, Paul  W. Dead crow reports and location of human West Nile virus cases, Chicago, 2002. Emerg Infect Dis. 2004;10:938–40.PubMedGoogle Scholar
  14. Theophilides  CN, Ahearn  SC, Grady  S, Merlino  M. Identifying West Nile virus risk areas: the Dynamic Continuous-Area Space-Time system. Am J Epidemiol. 2003;157:843–54. DOIPubMedGoogle Scholar
  15. Theophilides  CN, Ahearn  SC, Binkowski  ES, Paul  WS, Gibbs  K. First evidence of West Nile virus amplification and relationship to human infections. Int J Geogr Inf Sci. 2006;20:103–15. DOIGoogle Scholar
  16. Knox  G. Detection of low intensity epidemicity: application to cleft lip and palate. Br J Prev Soc Med. 1963;17:121–7.PubMedGoogle Scholar
  17. Knox  EG, Bartlett  MS. The detection of time–space interactions. Appl Stat. 1964;13:25–30. DOIGoogle Scholar
  18. Reisen  WK, Milby  MM, Meyer  RP. Population dynamics of adult Culex mosquitoes (Diptera: Culicidae) along the Kern River, Kern County, California, in 1990. J Med Entomol. 1992;29:531–43.PubMedGoogle Scholar
  19. Reeves  WC, Brookman  B, Hammon  WM. Studies on the flight range of certain Culex mosquitoes, using a fluorescent-dye marker, with notes on Culiseta and Anopheles. Mosq News. 1948;8:61–9.
  20. Russell  PF, Knipe  FW, Rao  TR, Putnam  P. Some experiments on flight range of Anopheles culicifacies. J Exp Zool. 1944;97:135–63. DOIGoogle Scholar
  21. Goddard  L, Roth  A, Reisen  WK, Scott  TW. Extrinsic incubation period of West Nile virus in four California Culex (Diptera: Culicidae) species. Proceedings of the Mosquito and Vector Control Association of California. 2003;71:70–5.
  22. McLean  RG, Ubico  SR, Docherty  DE, Hansen  WR, Sileo  L, McNamara  TS. West Nile virus transmission and ecology in birds. Ann N Y Acad Sci. 2001;951:54–7. DOIPubMedGoogle Scholar
  23. Weingartl  HM, Neufeld  JL, Copps  J, Marszal  P. Experimental West Nile virus infection in blue jays (Cyanocitta cristata) and crows (Corvus brachyrhynchos). Vet Pathol. 2004;41:362–70. DOIPubMedGoogle Scholar
  24. Cohen  J. A coefficient of agreement for nominal scales. Educ Psychol Meas. 1960;20:37–46. DOIGoogle Scholar
  25. Gerstman  BB. Epidemiology kept simple. 1st ed. New York: John Wiley and Sons, Inc.; 1998.
  26. Hom  A, Bonilla  D, Kjemtrup  A, Kramer  VL, Cahoon-Young  B, Barker  CM, Surveillance for mosquito-borne encephalitis virus activity and human disease, including West Nile virus, in California, 2005. Proceedings of the Mosquito and Vector Control Association of California. 2006;74:43–55.
  27. Landis  JR, Koch  GG. The measurement of observer agreement for categorical data. Biometrics. 1977;33:159–74. DOIPubMedGoogle Scholar
  28. Centers for Disease Control and Prevention. West Nile virus: clinical description. 2004 Sep 29 [cited 2011 Feb 28]. http://www.cdc.gov/ncidod/dvbid/westnile/clinicians/pdf/wnv-clinicaldescription
  29. California Department of Health Services. California arbovirus surveillance bulletin #21. Updated 2005 Jul 8. Sacramento (CA): The Department; 2005 [cited 2011 Feb 28].www.westnile.ca.gov/downloads.php?download_id=538&filename=arbobulletin_2005_21.pdf
  30. US Geological Survey. West Nile virus, human, 2005. Updated 2007 May 1. Reston (VA): The Survey; 2006 [cited 2011 Feb 28]. http://diseasemaps.usgs.gov/2005/wnv/wnv_us_human.html
  31. Elnaiem  DE, Kelley  K, Wright  S, Laffey  R, Yoshimura  G, Reed  M, Impact of aerial spraying of pyrethrin insecticide on Culex pipiens and Culex tarsalis (Diptera: Culicidae) abundance and West Nile virus infection rates in an urban/suburban area of Sacramento County, California. J Med Entomol. 2008;45:751–7. DOIPubMedGoogle Scholar
  32. Carney  RM, Husted  S, Jean  C, Glaser  C, Kramer  V. Efficacy of aerial spraying of mosquito adulticide in reducing incidence of West Nile virus, California, 2005. Emerg Infect Dis. 2008;14:747–54. DOIPubMedGoogle Scholar
  33. Eidson  M. “Neon needles” in a haystack: the advantages of passive surveillance for West Nile virus. Ann N Y Acad Sci. 2001;951:38–53. DOIPubMedGoogle Scholar
  34. Reisen  WK, Fang  Y, Martinez  VM. Avian host and mosquito (Diptera: Culicidae) vector competence determine the efficiency of West Nile and St. Louis encephalitis virus transmission. J Med Entomol. 2005;42:367–75. DOIPubMedGoogle Scholar
  35. Reisen  WK, Barker  CM, Carney  R, Lothrop  HD, Wheeler  S, Wilson  JL, Role of corvids in epidemiology of West Nile virus in southern California. J Med Entomol. 2006;43:356–67. DOIPubMedGoogle Scholar
  36. Ward  MP, Raim  A, Yaremych-Hamer  S, Lampman  R, Novak  RJ. Does the roosting behavior of birds affect transmission dynamics of West Nile virus? Am J Trop Med Hyg. 2006;75:350–5.PubMedGoogle Scholar
  37. Ruiz  MO, Tedesco  C, McTighe  TJ, Austin  C, Kitron  U. Environmental and social determinants of human risk during a West Nile virus outbreak in the greater Chicago area, 2002. Int J Health Geogr. 2004;3:8. DOIPubMedGoogle Scholar
  38. Ruiz  MO, Walker  ED, Foster  ES, Haramis  LD, Kitron  UD. Association of West Nile virus illness and urban landscapes in Chicago and Detroit. Int J Health Geogr. 2007;6:10. DOIPubMedGoogle Scholar
  39. Barber  LM, Schleier  III JJ, Peterson  RKD. Economic cost analysis of West Nile virus outbreak, Sacramento County, California, USA, 2005. Emerg Infect Dis. 2010;16:480–6. DOIPubMedGoogle Scholar

Main Article

1Current affiliation: Brown University, Providence, Rhode Island, USA.

2Current affiliation: University of British Columbia, Vancouver, British Columbia, Canada.

Page created: August 15, 2011
Page updated: August 15, 2011
Page reviewed: August 15, 2011
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
file_external