title: Reduced West Nile Virus Transmission Around Communal Roosts of Great-Tailed Grackle (Quiscalus mexicanus).
abstract: West Nile virus has caused several outbreaks among humans in the Phoenix metropolitan area (Arizona, southwest USA) within the last decade. Recent ecologic studies have implicated Culex quinquefasciatus and Culex tarsalis as the mosquito vectors and identified three abundant passerine birds-great-tailed grackle (Quiscalus mexicanus), house sparrow (Passer domesticus), and house finch (Haemorhous mexicanus)-as key amplifiers among vertebrates. Nocturnal congregations of certain species have been suggested as critical for late summer West Nile virus amplification. We evaluated the hypothesis that house sparrow (P. domesticus) and/or great-tailed grackle (Q. mexicanus) communal roost sites (n = 22 and n = 5, respectively) in a primarily suburban environment were spatially associated with West Nile virus transmission indices during the 2010 outbreak of human neurological disease in metropolitan Phoenix. Spatial associations between human case residences and communal roosts were non-significant for house sparrows, and were negative for great-tailed grackle. Several theories that explain these observations are discussed, including the possibility that grackle communal roosts are protective.
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO, 80521, USA, nck6@cdc.gov.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Komar
authors.forename: James M
authors.initials: JM
authors.lastname: Colborn
authors.forename: Kalanthe
authors.initials: K
authors.lastname: Horiuchi
authors.forename: Mark
authors.initials: M
authors.lastname: Delorey
authors.forename: Brad
authors.initials: B
authors.lastname: Biggerstaff
authors.forename: Dan
authors.initials: D
authors.lastname: Damian
authors.forename: Kirk
authors.initials: K
authors.lastname: Smith
authors.forename: John
authors.initials: J
authors.lastname: Townsend
mesh_terms: D000818:Animals; D001130:Arizona / Q000453:epidemiology; D003465:Culex / Q000821:virology; D006801:Humans; D046109:Passeriformes / Q000821:virology*; D011159:Population Surveillance; D012919:Social Behavior; D046370:Sparrows / Q000821:virology; D062206:Spatial Analysis; D013383:Suburban Population / Q000706:statistics & numerical data; D014901:West Nile Fever / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D014902:West Nile virus / Q000502:physiology*