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Molecular epidemiology of eastern equine encephalitis virus, New York.

Young DS, Kramer LD, Maffei JG, Dusek RJ, Backenson PB, Mores CN, Bernard KA, Ebel GD - Emerging Infect. Dis. (2008)

Bottom Line: To determine whether EEEV overwinters, is periodically reintroduced, or both, we sequenced the E2 and partial NSP3 coding regions of 42 EEEV isolates from New York State and the Eastern Seaboard of the United States.Strong clustering among strains isolated during epizootics in New York from 2003-2005, as well as from 1974-1975, demonstrates that EEEV has overwintered in this focus.This study provides molecular evidence for the introduction of southern EEEV strains to New York, followed by local amplification, perpetuation, and overwintering.

View Article: PubMed Central - PubMed

Affiliation: New York State Department of Health, Albany, New York, USA.

ABSTRACT
Perpetuation, overwintering, and extinction of eastern equine encephalitis virus (EEEV) in northern foci are poorly understood. We therefore sought to describe the molecular epidemiology of EEEV in New York State during current and past epizootics. To determine whether EEEV overwinters, is periodically reintroduced, or both, we sequenced the E2 and partial NSP3 coding regions of 42 EEEV isolates from New York State and the Eastern Seaboard of the United States. Our phylogenetic analyses indicated that derived subclades tended to contain southern strains that had been isolated before genetically similar northern strains, suggesting southern to northern migration of EEEV along the Eastern Seaboard. Strong clustering among strains isolated during epizootics in New York from 2003-2005, as well as from 1974-1975, demonstrates that EEEV has overwintered in this focus. This study provides molecular evidence for the introduction of southern EEEV strains to New York, followed by local amplification, perpetuation, and overwintering.

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A) United States map showing locations of eastern equine encephalitis virus strains sequenced in this study. New York State (NY) highlighted in blue; New Jersey (NJ), Virginia (VA), Florida (FL), Louisiana (LA) highlighted in gray. Map courtesy of www.theodora.com/maps, used with permission. B) New York counties where eastern equine encephalitis virus (EEEV) strains have been located (shaded). Dotted box indicates focus of most EEEV activity.
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Figure 1: A) United States map showing locations of eastern equine encephalitis virus strains sequenced in this study. New York State (NY) highlighted in blue; New Jersey (NJ), Virginia (VA), Florida (FL), Louisiana (LA) highlighted in gray. Map courtesy of www.theodora.com/maps, used with permission. B) New York counties where eastern equine encephalitis virus (EEEV) strains have been located (shaded). Dotted box indicates focus of most EEEV activity.

Mentions: Outbreaks of EEEV in New York have been observed periodically since 1952, when the virus was first detected in pheasants (7). Disease in humans and/or horses has been noted on Long Island, in the lower Hudson Valley, and in central upstate New York; the last known human case in New York occurred in 1983 in Onondaga County (8). Most EEEV activity in New York has occurred in counties bordering Oneida Lake in central upstate New York (Figure 1). Most of the activity in this region has been concentrated in the Big Bay–Toad Harbor Swamp complex in Oswego County and Cicero Swamp in Onondaga County (8). Culiseta melanura (Coquillett), the main enzootic vector of EEEV, breeds abundantly in these swamps (9). Localized epizootics in the counties of Oswego and Onondaga have been documented in a transmission focus during 1971–1977, 1982–1983, and 1990–1991 (8,10–13) and from 2003 to the present (2007; D.S. Young et al., unpub. data). Between these epizootic periods, EEEV was undetectable in horses and birds and only infrequently detected in mosquito pools (D.S. Young et al., unpub. data) (8). From 1992 through 1997 in upstate New York, EEEV was detected in 18 mosquito pools from Onondaga County (1994) and 3 mosquito pools from Oswego County (1996); no equine or avian cases were detected (D.S. Young et al., unpub. data). From 1998 through 2002, EEEV was not detected in mosquitoes or vertebrates in New York. However, in 2003, EEEV activity increased across New York with the emergence of the current epizootic (2003–2007) in the Onondaga and Oswego Counties region.


Molecular epidemiology of eastern equine encephalitis virus, New York.

Young DS, Kramer LD, Maffei JG, Dusek RJ, Backenson PB, Mores CN, Bernard KA, Ebel GD - Emerging Infect. Dis. (2008)

A) United States map showing locations of eastern equine encephalitis virus strains sequenced in this study. New York State (NY) highlighted in blue; New Jersey (NJ), Virginia (VA), Florida (FL), Louisiana (LA) highlighted in gray. Map courtesy of www.theodora.com/maps, used with permission. B) New York counties where eastern equine encephalitis virus (EEEV) strains have been located (shaded). Dotted box indicates focus of most EEEV activity.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2570827&req=5

Figure 1: A) United States map showing locations of eastern equine encephalitis virus strains sequenced in this study. New York State (NY) highlighted in blue; New Jersey (NJ), Virginia (VA), Florida (FL), Louisiana (LA) highlighted in gray. Map courtesy of www.theodora.com/maps, used with permission. B) New York counties where eastern equine encephalitis virus (EEEV) strains have been located (shaded). Dotted box indicates focus of most EEEV activity.
Mentions: Outbreaks of EEEV in New York have been observed periodically since 1952, when the virus was first detected in pheasants (7). Disease in humans and/or horses has been noted on Long Island, in the lower Hudson Valley, and in central upstate New York; the last known human case in New York occurred in 1983 in Onondaga County (8). Most EEEV activity in New York has occurred in counties bordering Oneida Lake in central upstate New York (Figure 1). Most of the activity in this region has been concentrated in the Big Bay–Toad Harbor Swamp complex in Oswego County and Cicero Swamp in Onondaga County (8). Culiseta melanura (Coquillett), the main enzootic vector of EEEV, breeds abundantly in these swamps (9). Localized epizootics in the counties of Oswego and Onondaga have been documented in a transmission focus during 1971–1977, 1982–1983, and 1990–1991 (8,10–13) and from 2003 to the present (2007; D.S. Young et al., unpub. data). Between these epizootic periods, EEEV was undetectable in horses and birds and only infrequently detected in mosquito pools (D.S. Young et al., unpub. data) (8). From 1992 through 1997 in upstate New York, EEEV was detected in 18 mosquito pools from Onondaga County (1994) and 3 mosquito pools from Oswego County (1996); no equine or avian cases were detected (D.S. Young et al., unpub. data). From 1998 through 2002, EEEV was not detected in mosquitoes or vertebrates in New York. However, in 2003, EEEV activity increased across New York with the emergence of the current epizootic (2003–2007) in the Onondaga and Oswego Counties region.

Bottom Line: To determine whether EEEV overwinters, is periodically reintroduced, or both, we sequenced the E2 and partial NSP3 coding regions of 42 EEEV isolates from New York State and the Eastern Seaboard of the United States.Strong clustering among strains isolated during epizootics in New York from 2003-2005, as well as from 1974-1975, demonstrates that EEEV has overwintered in this focus.This study provides molecular evidence for the introduction of southern EEEV strains to New York, followed by local amplification, perpetuation, and overwintering.

View Article: PubMed Central - PubMed

Affiliation: New York State Department of Health, Albany, New York, USA.

ABSTRACT
Perpetuation, overwintering, and extinction of eastern equine encephalitis virus (EEEV) in northern foci are poorly understood. We therefore sought to describe the molecular epidemiology of EEEV in New York State during current and past epizootics. To determine whether EEEV overwinters, is periodically reintroduced, or both, we sequenced the E2 and partial NSP3 coding regions of 42 EEEV isolates from New York State and the Eastern Seaboard of the United States. Our phylogenetic analyses indicated that derived subclades tended to contain southern strains that had been isolated before genetically similar northern strains, suggesting southern to northern migration of EEEV along the Eastern Seaboard. Strong clustering among strains isolated during epizootics in New York from 2003-2005, as well as from 1974-1975, demonstrates that EEEV has overwintered in this focus. This study provides molecular evidence for the introduction of southern EEEV strains to New York, followed by local amplification, perpetuation, and overwintering.

Show MeSH
Related in: MedlinePlus