Early warning system for west nile virus risk areas, california, usa

Ryan M. Carney, Sean C. Ahearn, Alan McConchie, Carol Glaser, Cynthia Jean, Chris Barker, Bborie Park, Kerry Padgett, Erin Parker, Ervic Aquino, Vicki Kramer

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


The Dynamic Continuous-Area Space-Time (DYCAST) system is a biologically based spatiotemporal model that uses public reports of dead birds to identify areas at high risk for West Nile virus (WNV) transmission to humans. In 2005, during a statewide epidemic of WNV (880 cases), the California Department of Public Health prospectively implemented DYCAST over 32,517 km 2 in California. Daily risk maps were made available online and used by local agencies to target public education campaigns, surveillance, and mosquito control. DYCAST had 80.8% sensitivity and 90.6% specificity for predicting human cases, and κ analysis indicated moderate strength of chance-adjusted agreement for >4 weeks. High-risk grid cells (populations) were identified an average of 37.2 days before onset of human illness; relative risk for disease was >39× higher than for low-risk cells. Although prediction rates declined in subsequent years, results indicate DYCAST was a timely and effective early warning system during the severe 2005 epidemic.

Original languageEnglish (US)
Pages (from-to)1445-1454
Number of pages10
JournalEmerging Infectious Diseases
Issue number8
StatePublished - Aug 1 2011

ASJC Scopus subject areas

  • Epidemiology
  • Microbiology (medical)
  • Infectious Diseases


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