title: Vector-host interactions and epizootiology of eastern equine encephalitis virus in Massachusetts.
abstract: Eastern equine encephalitis (EEE) virus is a highly pathogenic mosquito-borne zoonosis that is responsible for outbreaks of severe disease in humans and equines, resulting in high mortality or severe neurological impairment in most survivors. In the northeastern United States, EEE virus is maintained in an enzootic cycle involving the ornithophilic mosquito, Culiseta melanura (Coquillett) and passerine birds in freshwater swamp habitats. To evaluate the role of Cs. melanura and Culiseta morsitans (Theobald) in recent episodes of EEE virus activity in Massachusetts, we collected blood-fed mosquitoes between June, 2007, and October, 2008, from virus foci in 6 counties, and identified the source of blood meals by PCR amplification of mitochondrial cytochrome b gene and sequencing. Analysis of 529 Cs. melanura and 25 Cs. morsitans revealed that nearly 99% and 96% of mosquitoes, respectively, acquired blood meals solely from avian hosts. American Robin, Turdus migratorius Linnaeus was identified as the most common vertebrate host for Cs. melanura (21.7%, n=115), followed by Tufted Titmouse, Baeolophus bicolor (L.) (8.7%, n=46), Black-capped Chickadee, Poecile atricapillus (L.) (8.5%, n=45), Scarlet Tanager, Piranga olivacea (Gmelin) (6.8%, n=36), Field Sparrow, Spizella pusilla (Wilson) (6.2%, n=33), Northern Cardinal, Cardinalis cardinalis (L.) (5.7%, n=30), and other mostly Passeriformes birds. Mammalian-derived blood meals were identified as white-tailed deer, Odocoileus virginianus Zimmermann, domestic cow, Bos taurus L., and human, Homo sapiens L. There were 4 isolations of EEE virus, West Nile virus, and Highland J virus from Cs. melanura. Our results in conjunction with other lines of evidence, including reservoir competency, prevalence of antibody, and infection in nature, suggest that the American Robin, Tufted Titmouse, Black-capped Chickadee, and a few other passerine birds may play key roles in supporting EEE virus transmission in Massachusetts. Infrequent blood feeding of Cs. melanura on mammalian hosts, including humans, also indicates that this mosquito may occasionally contribute to epidemic/epizootic transmission of EEE virus in this region.
authors.affiliation: Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06504, USA. Goudarz.Molaei@ct.gov
authors.forename: Goudarz
authors.initials: G
authors.lastname: Molaei
authors.forename: Theodore G
authors.initials: TG
authors.lastname: Andreadis
authors.forename: Philip M
authors.initials: PM
authors.lastname: Armstrong
authors.forename: Michael C
authors.initials: MC
authors.lastname: Thomas
authors.forename: Timothy
authors.initials: T
authors.lastname: Deschamps
authors.forename: Esteban
authors.initials: E
authors.lastname: Cuebas-Incle
authors.forename: Walter
authors.initials: W
authors.lastname: Montgomery
authors.forename: Matthew
authors.initials: M
authors.lastname: Osborne
authors.forename: Sandra
authors.initials: S
authors.lastname: Smole
authors.forename: Priscilla
authors.initials: P
authors.lastname: Matton
authors.forename: Wayne
authors.initials: W
authors.lastname: Andrews
authors.forename: Curtis
authors.initials: C
authors.lastname: Best
authors.forename: Frank
authors.initials: F
authors.lastname: Cornine
authors.forename: Ellen
authors.initials: E
authors.lastname: Bidlack
authors.forename: Tony
authors.initials: T
authors.lastname: Texeira
mesh_terms: D000818:Animals; D009033:Culicidae / Q000502:physiology* / Q000821:virology; D045303:Cytochromes b / Q000235:genetics; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D004197:Disease Reservoirs; D004663:Encephalitis Virus, Eastern Equine / Q000235:genetics / Q000502:physiology*; D004683:Encephalomyelitis, Equine / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D005247:Feeding Behavior; D005260:Female; D054884:Host-Pathogen Interactions; D006801:Humans; D007303:Insect Vectors / Q000502:physiology* / Q000821:virology; D008322:Mammals; D008404:Massachusetts / Q000453:epidemiology; D008928:Mitochondria / Q000235:genetics; D046109:Passeriformes; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D016036:Seroepidemiologic Studies; D015047:Zoonoses
chemical_list: D004279:DNA, Viral; D045303:Cytochromes b