Declining Growth Rate of West Nile Virus in North America

ABSTRACT To determine the demographic history of West Nile virus (WNV) in North America, we employed a coalescent method to envelope coding region data sets for the NY99 and WN02 genotypes. Although the observed genetic diversities in both genotypes were of approximately the same age, the mean rate of epidemiological growth of the WN02 population was approximately three times that of the NY99 population, a finding compatible with the recent dominance of the former genotype. However, there has also been a marked decrease in the recent growth rate of WN02, suggesting that WNV has reached its peak prevalence in North America.

Download Full-text

Genetic variation in West Nile virus from naturally infected mosquitoes and birds suggests quasispecies structure and strong purifying selection

Journal of General Virology ◽

10.1099/vir.0.81015-0 ◽

2005 ◽

Vol 86 (8) ◽

pp. 2175-2183 ◽

Cited By ~ 137

Author(s):

Greta Jerzak ◽

Kristen A. Bernard ◽

Laura D. Kramer ◽

Gregory D. Ebel

Keyword(s):

Genetic Diversity ◽

West Nile Virus ◽

Consensus Sequence ◽

Purifying Selection ◽

Infected Mosquito ◽

Structural Protein ◽

Coding Region ◽

West Nile ◽

Transmission Cycle ◽

The Mean

Intrahost genetic diversity was analysed in naturally infected mosquitoes and birds to determine whether West Nile virus (WNV) exists in nature as a quasispecies and to quantify selective pressures within and between hosts. WNV was sampled from ten infected birds and ten infected mosquito pools collected on Long Island, NY, USA, during the peak of the 2003 WNV transmission season. A 1938 nt fragment comprising the 3′ 1159 nt of the WNV envelope (E) coding region and the 5′ 779 nt of the non-structural protein 1 (NS1) coding region was amplified and cloned and 20 clones per specimen were sequenced. Results from this analysis demonstrate that WNV infections are derived from a genetically diverse population of genomes in nature. The mean nucleotide diversity was 0·016 % within individual specimens and the mean percentage of clones that differed from the consensus sequence was 19·5 %. WNV sequences in mosquitoes were significantly more genetically diverse than WNV in birds. No host-dependent bias for particular types of mutations was observed and estimates of genetic diversity did not differ significantly between E and NS1 coding sequences. Non-consensus clones obtained from two avian specimens had highly similar genetic signatures, providing preliminary evidence that WNV genetic diversity may be maintained throughout the enzootic transmission cycle, rather than arising independently during each infection. Evidence of purifying selection was obtained from both intra- and interhost WNV populations. Combined, these data support the observation that WNV populations may be structured as a quasispecies and document strong purifying natural selection in WNV populations.

Download Full-text

Contrasted Epidemiological Patterns of West Nile Virus Lineages 1 and 2 Infections in France from 2015 to 2019

Pathogens ◽

10.3390/pathogens9110908 ◽

2020 ◽

Vol 9 (11) ◽

pp. 908 ◽

Cited By ~ 1

Author(s):

Cécile Beck ◽

Isabelle Leparc Goffart ◽

Florian Franke ◽

Gaelle Gonzalez ◽

Marine Dumarest ◽

...

Keyword(s):

Spatial Distribution ◽

West Nile Virus ◽

Invasive Disease ◽

Northern Italy ◽

Breaking Point ◽

Organ Donors ◽

West Nile ◽

Organ Donations ◽

History Of ◽

Lineage 2

Since 2015, annual West Nile virus (WNV) outbreaks of varying intensities have been reported in France. Recent intensification of enzootic WNV circulation was observed in the South of France with most horse cases detected in 2015 (n = 49), 2018 (n = 13), and 2019 (n = 13). A WNV lineage 1 strain was isolated from a horse suffering from West Nile neuro-invasive disease (WNND) during the 2015 episode in the Camargue area. A breaking point in WNV epidemiology was achieved in 2018, when WNV lineage 2 emerged in Southeastern areas. This virus most probably originated from WNV spread from Northern Italy and caused WNND in humans and the death of diurnal raptors. WNV lineage 2 emergence was associated with the most important human WNV epidemics identified so far in France (n = 26, including seven WNND cases and two infections in blood and organ donors). Two other major findings were the detection of WNV in areas with no or limited history of WNV circulation (Alpes-Maritimes in 2018, Corsica in 2018–2019, and Var in 2019) and distinct spatial distribution of human and horse WNV cases. These new data reinforce the necessity to enhance French WNV surveillance to better anticipate future WNV epidemics and epizootics and to improve the safety of blood and organ donations.

Download Full-text

West Nile Virus new to North America

Journal of Equine Veterinary Science ◽

10.1016/s0737-0806(99)80110-5 ◽

1999 ◽

Vol 19 (11) ◽

pp. 680-683

Author(s):

William E. Jones

Keyword(s):

West Nile Virus ◽

North America ◽

West Nile

Download Full-text

Potential Vectors of West Nile Virus in North America

Current Topics in Microbiology and Immunology - Japanese Encephalitis and West Nile Viruses ◽

10.1007/978-3-642-59403-8_12 ◽

2002 ◽

pp. 241-252 ◽

Cited By ~ 35

Author(s):

M. J. Turell ◽

M. R. Sardelis ◽

M. L. O’Guinn ◽

D. J. Dohm

Keyword(s):

West Nile Virus ◽

North America ◽

West Nile

Download Full-text

Population structure and demographic history of the chukar partridge Alectoris chukar in China

Current Zoology ◽

10.1093/czoolo/59.4.458 ◽

2013 ◽

Vol 59 (4) ◽

pp. 458-474 ◽

Cited By ~ 2

Author(s):

Sen Song ◽

Shijie Bao ◽

Ying Wang ◽

Xinkang Bao ◽

Bei An ◽

...

Keyword(s):

Genetic Diversity ◽

Gene Flow ◽

North America ◽

Demographic History ◽

Population Expansion ◽

Northwest China ◽

Population History ◽

Extant Species ◽

History Of ◽

Chukar Partridge

Abstract Pleistocene climate fluctuations have shaped the patterns of genetic diversity observed in extant species. Although the effects of recent glacial cycles on genetic diversity have been well studied on species in Europe and North America, genetic legacy of species in the Pleistocene in north and northwest of China where glaciations was not synchronous with the ice sheet development in the Northern Hemisphere or or had little or no ice cover during the glaciations’ period, remains poorly understood. Here we used phylogeographic methods to investigate the genetic structure and population history of the chukar partridge Alec-toris chukar in north and northwest China. A 1,152 – 1,154 bp portion of the mtDNA CR were sequenced for all 279 specimens and a total number of 91 haplotypes were defined by 113 variable sites. High levels of gene flow were found and gene flow estimates were greater than 1 for most population pairs in our study. The AMOVA analysis showed that 81% and 16% of the total genetic variability was found within populations and among populations within groups, respectively. The demographic history of chukar was examined using neutrality tests and mismatch distribution analyses and results indicated Late Pleistocene population expansion. Results revealed that most populations of chukar experienced population expansion during 0.027 ? 0.06 Ma. These results are at odds with the results found in Europe and North America, where population expansions occurred after Last Glacial Maximum (LGM, 0.023 to 0.018 Ma). Our results are not consistent with the results from avian species of Tibetan Plateau, either, where species experienced population expansion following the retreat of the extensive glaciation period (0.5 to 0.175 Ma).

Download Full-text

Early Evening Questing and Oviposition Activity by the Culex (Diptera: Culicidae) Vectors of West Nile Virus in Northeastern North America

Journal of Medical Entomology ◽

10.1093/jmedent/44.2.211 ◽

2007 ◽

Vol 44 (2) ◽

pp. 211-214 ◽

Cited By ~ 9

Author(s):

Michael R. Reddy ◽

Timothy J. Lepore ◽

Richard J. Pollack ◽

Anthony E. Kiszewski ◽

Andrew Spielman ◽

...

Keyword(s):

West Nile Virus ◽

North America ◽

West Nile ◽

Northeastern North America ◽

Early Evening

Download Full-text

West Nile Virus Devastates an American Crow Population

The Condor ◽

10.1093/condor/107.1.128 ◽

2005 ◽

Vol 107 (1) ◽

pp. 128-132 ◽

Cited By ~ 3

Author(s):

Carolee Caffrey ◽

Shauna C. R. Smith ◽

Tiffany J. Weston

Keyword(s):

West Nile Virus ◽

North America ◽

Late Summer ◽

Total Loss ◽

West Nile ◽

American Crow ◽

Corvus Brachyrhynchos ◽

American Crows

Abstract In its spread west across North America in 2002, West Nile virus (WNV) reached a population of marked American Crows (Corvus brachyrhynchos) in Stillwater, Oklahoma, in late summer. Within two months, 46 of 120 individuals were missing or known to be dead, 39 of which (33% of the population) are estimated to have died for WNV-related reasons. In 2003, 56 of 78 marked crows disappeared or were found dead between June and November. Five of the 28 juvenile losses were possibly unrelated to WNV, thus we estimate that 65% of our population died because of this pathogen in 2003. The total loss of 72% of population members, including 82% of juveniles, in a single year of WNV exposure raises concern for precipitous declines in American Crow populations in coming years. El Virus del Nilo Occidental Devasta una Población de Corvus brachyrhynchos Resumen. En su diseminación hacia el oeste de América del Norte durante 2002, el Virus del Nilo Occidental alcanzó a fines del verano una población marcada de Corvus brachyrhynchos en Stillwater, Oklahoma. En menos de dos meses, 46 de los 120 individuos registrados desaparecieron o murieron, 39 de los cuales (33% de la población) estimamos que murieron por causas relacionadas con el virus. En 2003, 56 de los 78 cuervos marcados desaparecieron o fueron encontrados muertos entre junio y noviembre. Cinco de las 28 pérdidas de juveniles posiblemente no estuvieron relacionadas con el virus, por lo que estimamos que el 65% de nuestra población murió a causa de este patógeno en 2003. La pérdida total del 72% de los miembros de la población, incluyendo el 82% de los juveniles, en un solo año de exposición al virus plantea preocupaciones en cuanto a la posibilidad de una disminución precipitada de las poblaciones de C. brachyrhynchos en los próximos años.

Download Full-text