title: Early warning system for West Nile virus risk areas, California, USA.
abstract: 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 km2 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 k 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.
authors.affiliation: California Department of Public Health, Richmond, California, USA. ryan_carney@brown.edu
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Carney
authors.forename: Sean C
authors.initials: SC
authors.lastname: Ahearn
authors.forename: Alan
authors.initials: A
authors.lastname: McConchie
authors.forename: Carol
authors.initials: C
authors.lastname: Glasner
authors.forename: Cynthia
authors.initials: C
authors.lastname: Jean
authors.forename: Chris
authors.initials: C
authors.lastname: Barker
authors.forename: Bborie
authors.initials: B
authors.lastname: Park
authors.forename: Kerry
authors.initials: K
authors.lastname: Padgett
authors.forename: Erin
authors.initials: E
authors.lastname: Parker
authors.forename: Ervic
authors.initials: E
authors.lastname: Aquino
authors.forename: Vicki
authors.initials: V
authors.lastname: Kramer
mesh_terms: D000818:Animals; D001717:Birds / Q000821:virology; D002140:California / Q000453:epidemiology; D003465:Culex / Q000821:virology; D040362:Geographic Information Systems; D006801:Humans; D007303:Insect Vectors / Q000821:virology; D012307:Risk Factors; D012680:Sensitivity and Specificity; D018571:Sentinel Surveillance / Q000662:veterinary*; D013029:Space-Time Clustering; D014901:West Nile Fever / Q000453:epidemiology / Q000635:transmission* / Q000662:veterinary; D014902:West Nile virus / Q000302:isolation & purification*