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United States Articles found through PubMed 2000-2012

Description

West Nile Virus (WNV) is a mosquito-borne virus that can infect humans. Originally known in East Africa, WNV has now spread throughout the world. The first case of WNV in the western hemisphere was identified in New York in 1999, and within 5 years the disease had spread throughout the United States and into Canada, Latin America, and the Caribbean. While most of WNV infections cause no symptoms, the remaining cases show flu-like symptoms, and can lead to neurological disease or death.

latest article added on November 2013

ArticleFirst AuthorPublished
Cerebrospinal fluid cytology in seasonal epidemic West Nile virus meningo-encephalitisRawal, Ajay2006

Cerebrospinal fluid cytology in seasonal epidemic West Nile virus meningo-encephalitis

Keywords

West Nile virus;cytology;cerebrospinal fluid;pleocytosis, WNV

Abstract

The incidence of West Nile Virus (WNV) infection has progressively increased in North America since the first epidemic in 1999. Formal scholarly documentation of cerebrospinal fluid (CSF) cytology changes in patients with WNV infection is limited. We report our experience with CSF cytospins from a population of consecutive patients with documented CSF WNV-specific IgM. Thirty-two patients (12 male, 20 female) with a median age of 52 yr (range, 19–88) diagnosed with WNV meningo-encephalitis were studied. Symptoms were present for a mean of 5 days (range, 1–14) prior to lumbar puncture. CSF proteins were elevated in 94% of patients (30/32) with a mean value of 79 mg/dl (range, 36–185). CSF glucose was normal to elevated in all cases. All cytomorphologically adequate samples demonstrated a pleocytosis with a mean of 156 cells/mm3 (range, 13–683). Nearly, all (26/28) patients showed increased CSF neutrophils- mean 43% (range, 1–83). Mean lymphocyte and monocyte fractions were 44% (range, 8–85) and 14% (range, 2–27), respectively. Three cases showed 1–4% plasma cells. Mean total leukocyte counts (TLC) (197 cells/mm3) and mean neutrophil fractions (50%) were greater in patients sampled within the first 3 days of symptoms than in those sampled beyond day 3 (mean TLC, 126 cells/mm3; mean neutrophil fraction, 37%). Relative lymphocyte proportions increased from a mean of 39 to 48% after 3 days of illness. WNV should be considered as a potential etiology of infectious CSF pleocytosis in the North American late summer and early fall seasons.

Authors

Rawal, Ajay, Gavin, Patrick J. and Sturgis, Charles D.

Year Published

2006

Publication

Diagnostic Cytopathology

Locations
DOI

10.1002/dc.20410

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16511849

Modeling the Spatial Distribution of Mosquito Vectors for West Nile Virus in Connecticut, USADiuk-Wasser, Maria A.2006

Modeling the Spatial Distribution of Mosquito Vectors for West Nile Virus in Connecticut, USA

Keywords

WNV

Abstract

The risk of transmission of West Nile virus (WNV) to humans is associated with the density of infected vector mosquitoes in a given area. Current technology for estimating vector distribution and abundance is primarily based on Centers for Disease Control and Prevention (CDC) light trap collections, which provide only point data. In order to estimate mosquito abundance in areas not sampled by traps, we developed logistic regression models for five mosquito species implicated as the most likely vectors of WNV in Connecticut. Using data from 32 traps in Fairfield County from 2001 to 2003, the models were developed to predict high and low abundance for every 30 × 30 m pixel in the County. They were then tested with an independent dataset from 16 traps in adjacent New Haven County. Environmental predictors of abundance were extracted from remotely sensed data. The best predictive models included non-forested areas for Culex pipiens, surface water and distance to estuaries for Cx. salinarius, surface water and grasslands/agriculture for Aedes vexans and seasonal difference in the normalized difference vegetation index and distance to palustrine habitats for Culiseta melanura. No significant predictors were found for Cx. restuans. The sensitivity of the models ranged from 75% to 87.5% and the specificity from 75% to 93.8%. In New Haven County, the models correctly classified 81.3% of the traps for Cx. pipiens, 75.0% for Cx. salinarius, 62.5% for Ae. vexans, and 75.0% for Cs. melanura. Continuous surface maps of habitat suitability were generated for each species for both counties, which could contribute to future surveillance and intervention activities.

Authors

Andreadis, Theodore G., Fish, Durland, Diuk-Wasser, Maria A. and Brown, Heidi E.

Year Published

2006

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2006.6.283

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16989568

Avian virulence and thermostable replication of the North American strain of West Nile virusKinney, R. M.2006

Avian virulence and thermostable replication of the North American strain of West Nile virus

Keywords

WNV

Abstract

The NY99 genotype of West Nile virus (WNV) introduced into North America has demonstrated high virulence for American crows (AMCRs), whilst a closely related WNV strain (KEN-3829) from Kenya exhibits substantially reduced virulence in AMCRs [Brault, A. C., Langevin, S. A., Bowen, R. A., Panella, N. A., Biggerstaff, B. J., Miller, B. R. & Nicholas, K. (2004). Emerg Infect Dis 10, 2161–2168]. Viruses rescued from infectious cDNA clones of both the NY99 and KEN-3829 strains demonstrated virulence comparable to that of their parental strains in AMCRs. To begin to define parameters that might explain the different virulence phenotypes between these two viruses, temperature-sensitivity assays were performed for both viruses at the high temperatures experienced in viraemic AMCRs. Growth curves of the two WNV strains were performed in African green monkey kidney (Vero; 37–42 °C) and duck embryonic fibroblast (DEF; 37–45 °C) cells cultured at temperatures that were tolerated by the cell line. Unlike the NY99 virus, marked decreases in KEN-3829 viral titres were detected between 36 and 120 h post-infection (p.i.) at temperatures above 43 °C. Replication of KEN-3829 viral RNA was reduced 6500-fold at 72 h p.i. in DEF cells incubated at 44 °C relative to levels of intracellular virus-specific RNA measured at 37 °C. In contrast, replication of virus derived from the NY99 infectious cDNA at 44 °C demonstrated only a 17-fold reduction in RNA level. These results indicated that the ability of WNV NY99 to replicate at the high temperatures measured in infected AMCRs could be an important factor leading to the increased avian virulence and emergence of this strain of WNV.

Authors

Kinney, R. M., Huang, C. Y.-H., Whiteman, M. C., Bowen, R. A., Langevin, S. A., Miller, B. R. and Brault, A. C.

Year Published

2006

Publication

Journal of General Virology

Locations
DOI

10.1099/vir.0.82299-0

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/17098976

Factors Affecting the Geographic Distribution of West Nile Virus in Georgia, USA: 2002–2004Gibbs, Samantha E.J.2006

Factors Affecting the Geographic Distribution of West Nile Virus in Georgia, USA: 2002–2004

Keywords

WNV

Abstract

The distribution of West Nile virus (WNV) is dependent on the occurrence of both susceptible avian reservoir hosts and competent mosquito vectors. Both factors can be influenced by geographic variables such as land use/landcover, elevation, human population density, physiographic region, and temperature. The current study uses geographic information systems (GIS) and logistic regression analyses to model the distribution of WNV in the state of Georgia based on a wild bird indicator system, and to identify human and environmental predictor variables that are important in the determination of WNV distribution. A database for Georgia was constructed that included (1) location points of all the avian samples tested for WNV, (2) local land use classifications, including temperature, physiographic divisions, land use/landcover, and elevation, (3) human demographic data from the U.S. Census, and (4) statistics summarizing land cover, elevation, and climate within a 1-km-radius landscape around each sample point. Logistic regression analysis was carried out using the serostatus of avian collection sites as the dependent variable. Temperature, housing density, urban/suburban land use, and mountain physiographic region were important variables in predicting the distribution of WNV in the state of Georgia. While weak, the positive correlation between WNV-antibody positive sites and the urban/suburban environment was consistent throughout the study period. The risks associated with WNV endemicity appear to be increased in urban/ suburban areas and decreased in the mountainous region of the state. This information may be used in addressing regional public health needs and mosquito control programs.

Authors

Stallknecht, David E., Gibbs, Samantha E.J., Wimberly, Michael C., Madden, Marguerite, Masour, Janna and Yabsley, Michael J.

Year Published

2006

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2006.6.73

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16584329

West Nile Virus Antibodies in Avian Species of Georgia, USA: 2000–2004Gibbs, Samantha E.J.2006

West Nile Virus Antibodies in Avian Species of Georgia, USA: 2000–2004

Keywords

WNV

Abstract

West Nile virus (WNV) was first isolated in the state of Georgia in the summer of 2001. As amplifying hosts of WNV, avian species play an important role in the distribution and epidemiology of the virus. The objective of this study was to identify avian species that are locally involved as potential amplifying hosts of WNV and can serve as indicators of WNV transmission over the physiographic and land use variation present in the southeastern United States. Avian serum samples (n = 14,077) from 83 species of birds captured throughout Georgia during the summers of 2000–2004 were tested by a plaque reduction neutralization test for antibodies to WNV and St. Louis encephalitis virus. Over the 5-year period, WNV-neutralizing antibodies were detected in 869 (6.2%) samples. The WNV seroprevalence increased significantly throughout the study and was species dependent. The highest antibody prevalence rates were detected in rock pigeons (Columba livia), northern cardinals (Cardinalis cardinalis), common ground doves (Columbina passerina), grey catbirds (Deumetella carolinensis), and northern mockingbirds (Mimus polyglottos). Northern cardinals, in addition to having high geometric mean antibody titers and seroprevalence rates, were commonly found in all land use types and physiographic regions. Rock pigeons, common ground doves, grey catbirds, and northern mockingbirds, although also having high seroprevalence rates and high antibody titers against WNV, were more restricted in their distribution and therefore may be of more utility when attempting to assess exposure rates in specific habitat types. Of all species tested, northern cardinals represent the best potential avian indicator species for widespread serologic-based studies of WNV throughout Georgia due to their extensive range, ease of capture, and high antibody rates and titers. Due to the large geographic area covered by this species, their utility as a WNV sentinel species may include most of the eastern United States.

Authors

Stallknecht, David E., Gibbs, Samantha E.J., Yabsley, Michael J., Allison, Andrew B., Mead, Daniel G. and Wilcox, Benjamin R.

Year Published

2006

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2006.6.57

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16584328

Field-Caught Culex erythrothorax Larvae Found Naturally Infected with West Nile Virus in Grand County, UtahPhillips, Robert A.2006

Field-Caught Culex erythrothorax Larvae Found Naturally Infected with West Nile Virus in Grand County, Utah

Keywords

West Nile virus, Culex erythrothorax, vertical transmission, transovarial transmission, overwintering, WNV

Abstract

Culex erythrothorax larvae were collected from a bulrush-cattail marsh near Moab, Grand County, Utah, October 28, 2004, and found positive for West Nile virus (WNV) RNA by real-time reverse-transcriptase polymerase chain reaction (RT-PCR). This demonstrates WNV vertical transmission in this species in the wild and suggests that vertical transmission in overwintering Cx. erythrothorax larvae may contribute to WNV overwintering.

Authors

Phillips, Robert A. and Christensen, Kimberly

Year Published

2006

Publication

Journal of the American Mosquito Control Association

Locations
DOI

10.2987/8756-971X(2006)22[561:FCELFN]2.0.CO;2

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/17067064

Survey of Aedes triseriatus (Diptera: Culicidae) for Lacrosse Encephalitis Virus and West Nile Virus in Lorain County, OhioScheidler, Lydia C.2006

Survey of Aedes triseriatus (Diptera: Culicidae) for Lacrosse Encephalitis Virus and West Nile Virus in Lorain County, Ohio

Keywords

West Nile virus, La Crosse encephalitis virus, surveillance, arbovirus, Aedes triseriatus, WNV

Abstract

From June through September 2003, we conducted a survey of female Aedes triseriatus (Say) for infection with La Crosse encephalitis virus (family Bunyaviridae, genus Orthobunyavirus, LACV) and West Nile virus (family Flaviviridae, genus Flavivirus, WNV) at three locations in Lorain County, Ohio. To determine infection rate and seasonal variation of both viruses in the Ae. triseriatus population, Ae. triseriatus were collected weekly by using gravid traps and CO2-baited CDC light traps and tested for virus by using reverse transcriptase polymerase chain reaction. In total, 170 pools comprised of 2,143 females were tested for LACV, of which seven were positive; the maximum likelihood estimate of infection rate combined throughout the season was 3.22/1,000. None of 170 pools comprised of 2,158 females tested for WNV were positive. LACV-positive pools were detected between late July and early September.

Authors

Scheidler, Lydia C., Dunphy-daly, Meagan M., White, Bradley J., Andrew, David R., Mans, Nicole Z. and Garvin, Mary C.

Year Published

2006

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/0022-2585(2006)43[589:SOATDC]2.0.CO;2

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16739420

Discovering Spatio-Temporal Models of the Spread of West Nile VirusOrme-Zavaleta, Jennifer2006

Discovering Spatio-Temporal Models of the Spread of West Nile Virus

Keywords

Community model;infectious disease;integrated risk analysis;probabilistic;relational model;West Nile virus, WNV

Abstract

Emerging infectious diseases are characterized by complex interactions among disease agents, vectors, wildlife, humans, and the environment.(1–3) Since the appearance of West Nile virus (WNV) in New York City in 1999, it has infected over 8,000 people in the United States, resulting in several hundred deaths in 46 contiguous states.(4) The virus is transmitted by mosquitoes and maintained in various bird reservoir hosts.(5) Its unexpected introduction, high morbidity, and rapid spread have left public health agencies facing severe time constraints in a theory-poor environment, dependent largely on observational data collected by independent survey efforts and much uncertainty. Current knowledge may be expressed as a priori constraints on models learned from data. Accordingly, we applied a Bayesian probabilistic relational approach to generate spatially and temporally linked models from heterogeneous data sources. Using data collected from multiple independent sources in Maryland, we discovered the integrated context in which infected birds are plausible indicators for positive mosquito pools and human cases for 2001 and 2002.

Authors

Orme-Zavaleta, Jennifer, Jorgensen, Jane, D'Ambrosio, Bruce, Altendorf, Eric and Rossignol, Philippe A.

Year Published

2006

Publication

Risk Analysis

Locations
DOI

10.1111/j.1539-6924.2006.00738.x

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16573630

COMPARISON OF MOSQUITO TRAPPING METHOD EFFICACY FOR WEST NILE VIRUS SURVEILLANCE IN NEW MEXICODiMenna, Mark A.2006

COMPARISON OF MOSQUITO TRAPPING METHOD EFFICACY FOR WEST NILE VIRUS SURVEILLANCE IN NEW MEXICO

Keywords

Mosquitoes, trapping methods, New Mexico, Rio Grande, West Nile virus, WNV

Abstract

As part of the West Nile virus surveillance program for the state of New Mexico, 13 sites along the Rio Grande River were sampled for mosquitoes during spring and summer 2003. We evaluated 3 different trapping procedures for their effectiveness at capturing selected species of mosquitoes. The 3 methods used were a dry ice-baited Centers for Disease Control and Prevention (CDC) light trap set 1.5 m above the ground (standard method), a CDC light trap suspended within the forest canopy, and a gravid trap set on the ground. Thirteen sites were sampled for 10 1-night periods biweekly from May through September. The relative numbers of captured Culex tarsalis, Cx. salinarius, Cx. quinquefasciatus, and Aedes vexans as well as the numbers of total recorded captures of all species were compared for each trapping method. Significant differences were observed for each species by location and by trapping method. Culex tarsalis was most commonly caught in canopy or standard CDC traps, especially in cottonwood bosque. Culex salinarius was found most frequently in association with marshy water, and was most often caught in gravid or standard light traps. Culex quinque-fasciatus was captured almost exclusively in gravid traps within urban areas. Aedes vexans was primarily sampled in standard CDC light traps and found most frequently in wooded areas near floodplains. With the exception of Cx. quinquefasciatus, no species was collected significantly more frequently in gravid or canopy traps than in the standard CDC light trap. Our findings do not support altering the methods currently used in New Mexico, namely, the use of 1.5-m CDC light traps and gravid traps. An increased use of gravid traps seems to be warranted in monitoring urban vector populations (specifically Cx. quinquefasciatus and Cx. salinarius) that may be involved in human transmission.

Authors

Parmenter, Robert R., DiMenna, Mark A., Bueno, Rudy, Norris, Douglas E., Sheyka, Jeff M., Molina, Josephine L., LaBeau, Elisa M., Hatton, Elizabeth S. and Glass, Gregory E.

Year Published

2006

Publication

Journal of the American Mosquito Control Association

Locations
DOI

10.2987/8756-971X(2006)22[246:COMTME]2.0.CO;2

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/17019770

Avian diversity and West Nile virus: testing associations between biodiversity and infectious disease riskEzenwa, V. O2006

Avian diversity and West Nile virus: testing associations between biodiversity and infectious disease risk

Keywords

West Nile virus, vector-borne disease, zoonoses, dilution effect, biodiversity, birds, WNV

Abstract

The emergence of several high profile infectious diseases in recent years has focused attention on our need to understand the ecological factors contributing to the spread of infectious diseases. West Nile virus (WNV) is a mosquito-borne zoonotic disease that was first detected in the United States in 1999. The factors accounting for variation in the prevalence of WNV are poorly understood, but recent ideas suggesting links between high biodiversity and reduced vector-borne disease risk may help account for distribution patterns of this disease. Since wild birds are the primary reservoir hosts for WNV, we tested associations between passerine (Passeriform) bird diversity, non-passerine (all other orders) bird diversity and virus infection rates in mosquitoes and humans to examine the extent to which bird diversity is associated with WNV infection risk. We found that non-passerine species richness (number of non-passerine species) was significantly negatively correlated with both mosquito and human infection rates, whereas there was no significant association between passerine species richness and any measure of infection risk. Our findings suggest that non-passerine diversity may play a role in dampening WNV amplification rates in mosquitoes, minimizing human disease risk.

Authors

Ezenwa, V. O, Godsey, M. S, King, R. J and Guptill, S. C

Year Published

2006

Publication

Proceedings of the Royal Society B: Biological Sciences

Locations
DOI

10.1098/rspb.2005.3284

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16519242

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