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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
Identification of Environmental Covariates of West Nile Virus Vector Mosquito Population AbundanceTrawinski, Patricia R.2010

Identification of Environmental Covariates of West Nile Virus Vector Mosquito Population Abundance

Keywords

WNV

Abstract

The rapid spread of West Nile virus (WNv) in North America is a major public health concern. Culex pipiens-restuans is the principle mosquito vector of WNv in the northeastern United States while Aedes vexans is an important bridge vector of the virus in this region. Vector mosquito abundance is directly dependent on physical environmental factors that provide mosquito habitats. The objective of this research is to determine landscape elements that explain the population abundance and distribution of WNv vector mosquitoes using stepwise linear regression. We developed a novel approach for examining a large set of landscape variables based on a land use and land cover classification by selecting variables in stages to minimize multicollinearity. We also investigated the distance at which landscape elements influence abundance of vector populations using buffer distances of 200, 400, and 1000 m. Results show landscape effects have a significant impact on Cx. pipiens-estuans population distribution while the effects of landscape features are less important for prediction of Ae. vexans population distributions. Cx. pipiens-restuans population abundance is positively correlated with human population density, housing unit density, and urban land use and land cover classes and negatively correlated with age of dwellings and amount of forested land.

Authors

Trawinski, Patricia R. and Mackay, D. Scott

Year Published

2010

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2008.0063

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20482343

PATHOLOGY ASSOCIATED WITH WEST NILE VIRUS INFECTIONS IN THE YELLOW-BILLED MAGPIE (PICA NUTTALLI): A CALIFORNIA ENDEMIC BIRDErnest, Holly B.2010

PATHOLOGY ASSOCIATED WITH WEST NILE VIRUS INFECTIONS IN THE YELLOW-BILLED MAGPIE (PICA NUTTALLI): A CALIFORNIA ENDEMIC BIRD

Keywords

Arbovirus, corvid, necrosis, pathology, Pica nuttalli, species of concern, West Nile virus, Yellow-billed Magpie, WNV

Abstract

Yellow-billed Magpies (Pica nuttalli, Corvidae) are found exclusively in central California and have experienced alarming West Nile virus (WNV)–associated mortality since 2004. The first reported case of WNV in the species was reported in July 2004. Subsequently, 81% (304/374) of dead magpies submitted that year to the California Department of Health Services Dead Bird Surveillance Program were WNV positive by polymerase chain reaction (PCR) test. We studied 43 magpie carcasses collected in 2004 and observed distinctive lesions in 24 birds that tested positive for WNV. Lesions included vasculitis and necrosis, and organs affected included brain, heart, liver, and gastrointestinal tract. From the severity of lesions observed, we suspect that a rapid onset of morbidity and mortality occurs with the Yellow-billed Magpie. Examination of bird survey data indicates that Yellow-billed Magpie abundance declined coincidentally with the onset of WNV in California. The home range and habitat of the species are nested within known areas of WNV transmission. Yellow-billed Magpies may be at risk of a decline and population bottleneck. Observations and experience with the Yellow-billed Magpie and WNV may provide insights for other endangered corvids that have not yet been exposed to WNV, including the Hawaiian Crow (Corvus hawaiiensis) and Island Scrub Jay (Aphelocoma insularis).

Authors

Ernest, Holly B., Woods, Leslie W. and Hoar, Bruce R.

Year Published

2010

Publication

Journal of Wildlife Diseases

Locations
DOI

10.7589/0090-3558-46.2.401

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20688633

Test of Recrudescence Hypothesis for Overwintering of West Nile Virus in Gray CatbirdsOwen, J. C.2010

Test of Recrudescence Hypothesis for Overwintering of West Nile Virus in Gray Catbirds

Keywords

West Nile virus, overwintering, Dumetella carolinensis, testosterone, migration, WNV

Abstract

West Nile virus is a pathogen of concern for both human and wildlife health, Although many aspects of the ecology of West Nile virus are well understood, the mechanisms by which this and similar mosquito-borne viruses overwinter and become reinitiated each spring in temperate regions is not known. A thorough understanding of this mechanism is crucial to risk assessment and development of control strategies. One of the hypotheses to explain the mechanism by which this virus persists from year to year is the spring recrudescence of latent virus in avian reservoir hosts. Stress-related immunosuppression is implicated in the recrudescence of latent viruses in birds. We tested the spring recrudescence hypothesis in a controlled laboratory experiment using hatching-year gray catbirds (Dumatella carolinensis) captured in northern Ohio (July–August 2006), Catbirds (n = 60) were experimentally infected (September 2006) and later examined for the effects of immuno-suppression through exogenous hormones and artificially induced migratory disposition, We found no effect of either testosterone or migratory behavior on infection status in any of the treatment birds. Moreover, we detected no viral RNA in the kidney, spleen, brain, or liver upon necropsy at 24 wk postinfection.

Authors

Owen, J. C., Moore, F. R., Williams, A. J., Ward, M. P., Beveroth, T. A., Miller, E. A., Wilson, L. C., Morley, V. J., Abbey-Lee, R. N., Veeneman, B. A., Derussy, B. M., McWhorter, M. S. and Garvin, M. C.

Year Published

2010

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/ME09035

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20496593

Prevalence and Pathology of West Nile Virus in Naturally Infected House Sparrows, Western Nebraska, 2008O'Brien, V. A.2010

Prevalence and Pathology of West Nile Virus in Naturally Infected House Sparrows, Western Nebraska, 2008

Keywords

WNV

Abstract

Nestling birds are rarely sampled in the field for most arboviruses, yet they may be important in arbovirus amplification cycles. We sampled both nestling and adult house sparrows (Passer domesticus) in western Nebraska for West Nile virus (WNV) or WNV-specific antibodies throughout the summer of 2008 and describe pathology in naturally infected nestlings. Across the summer, 4% of nestling house sparrows were WNV-positive; for the month of August alone, 12.3% were positive. Two WNV-positive nestlings exhibited encephalitis, splenomegaly, hepatic necrosis, nephrosis, and myocarditis. One nestling sparrow had large mural thrombi in the atria and ventricle and immunohistochemical staining of WNV antigen in multiple organs including the wall of the aorta and pulmonary artery; cardiac insufficiency thus may have been a cause of death. Adult house sparrows showed an overall seroprevalence of 13.8% that did not change significantly across the summer months. The WNV-positive nestlings and the majority of seropositive adults were detected within separate spatial clusters. Nestling birds, especially those reared late in the summer when WNV activity is typically greatest, may be important in virus amplification.

Authors

O'Brien, V. A., Meteyer, C. U., Reisen, W. K., Ip, H. S. and Brown, C. R.

Year Published

2010

Publication

American Journal of Tropical Medicine and Hygiene

Locations
DOI

10.4269/ajtmh.2010.09-0515

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20439979

Mosquito politics: Local vector control policies and the spread of West Nile Virus in the Chicago regionTedesco, Carmen2010

Mosquito politics: Local vector control policies and the spread of West Nile Virus in the Chicago region

Keywords

West Nile Virus; Mosquito abatement; Political Ecology; Clustering; Chicago; Mosquito control, WNV

Abstract

Differences in mosquito control practices at the local level involve the interplay of place, scale and politics. During the Chicago West Nile Virus (WNV) outbreak of 2002, mosquito abatement districts represent distinct suburban clusters of human WNV cases, independent of characteristics of the local population, housing and physical environment. We examine how the contrasting actions of four districts reveal a distinct local politics of mosquito control that may have contributed to local-scale geographic differences in WNV incidence. This politics is rooted in political, economic and philosophical differences within and between administrative boundaries.

Authors

Tedesco, Carmen, Ruiz, Marilyn and McLafferty, Sara

Year Published

2010

Publication

Health & Place

Locations
DOI

10.1016/j.healthplace.2010.08.003

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20709590

Modeled response of the West Nile virus vector Culex quinquefasciatus to changing climate using the dynamic mosquito simulation modelMorin, Cory W.2010

Modeled response of the West Nile virus vector Culex quinquefasciatus to changing climate using the dynamic mosquito simulation model

Keywords

WNV

Abstract

Climate can strongly influence the population dynamics of disease vectors and is consequently a key component of disease ecology. Future climate change and variability may alter the location and seasonality of many disease vectors, possibly increasing the risk of disease transmission to humans. The mosquito species Culex quinquefasciatus is a concern across the southern United States because of its role as a West Nile virus vector and its affinity for urban environments. Using established relationships between atmospheric variables (temperature and precipitation) and mosquito development, we have created the Dynamic Mosquito Simulation Model (DyMSiM) to simulate Cx. quinquefasciatus population dynamics. The model is driven with climate data and validated against mosquito count data from Pasco County, Florida and Coachella Valley, California. Using 1-week and 2-week filters, mosquito trap data are reproduced well by the model (P < 0.0001). Dry environments in southern California produce different mosquito population trends than moist locations in Florida. Florida and California mosquito populations are generally temperature-limited in winter. In California, locations are water-limited through much of the year. Using future climate projection data generated by the National Center for Atmospheric Research CCSM3 general circulation model, we applied temperature and precipitation offsets to the climate data at each location to evaluate mosquito population sensitivity to possible future climate conditions. We found that temperature and precipitation shifts act interdependently to cause remarkable changes in modeled mosquito population dynamics. Impacts include a summer population decline from drying in California due to loss of immature mosquito habitats, and in Florida a decrease in late-season mosquito populations due to drier late summer conditions.

Authors

Morin, Cory W. and Comrie, Andrew C.

Year Published

2010

Publication

International Journal of Biometeorology

Locations
DOI

10.1007/s00484-010-0349-6

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20683620

Hydrologic Conditions Describe West Nile Virus Risk in ColoradoShaman, Jeffrey2010

Hydrologic Conditions Describe West Nile Virus Risk in Colorado

Keywords

WNV

Abstract

We examine the relationship between hydrologic variability and the incidence of human disease associated with West Nile virus (WNV; family Flaviviridae, genus Flavivirus) infection (hereafter termed "human WN cases") in Colorado from 2002 to 2007. We find that local hydrologic conditions, as simulated by the Mosaic hydrology model, are associated with differences in human WN cases. In Colorado's eastern plains, wetter spring conditions and drier summer conditions predict human WN cases. In Colorado's western mountains, drier spring and summer conditions weakly predict human WN cases. These findings support two working hypotheses: (1) wet spring conditions increase the abundance of Culex tarsalis vectors in the plains, and (2) dry summer conditions, and respondent irrigational practices during such droughts, favor Cx. pipiens and Cx. tarsalis abundance throughout Colorado. Both of these processes potentially increase the local vector-to-host ratio, favoring WNV amplification among competent avian hosts and bridging to humans.

Authors

Shaman, Jeffrey, Day, Jonathan F. and Komar, Nicholas

Year Published

2010

Publication

International Journal of Environmental Research and Public Health

Locations
DOI

10.3390/ijerph7020494

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20616987

Local impact of temperature and precipitation on West Nile virus infection in Culex species mosquitoes in northeast Illinois, USARuiz, Marilyn O2010

Local impact of temperature and precipitation on West Nile virus infection in Culex species mosquitoes in northeast Illinois, USA

Keywords

WNV

Abstract

Background Models of the effects of environmental factors on West Nile virus disease risk have yielded conflicting outcomes. The role of precipitation has been especially difficult to discern from existing studies, due in part to habitat and behavior characteristics of specific vector species and because of differences in the temporal and spatial scales of the published studies. We used spatial and statistical modeling techniques to analyze and forecast fine scale spatial (2000 m grid) and temporal (weekly) patterns of West Nile virus mosquito infection relative to changing weather conditions in the urban landscape of the greater Chicago, Illinois, region for the years from 2004 to 2008. Results Increased air temperature was the strongest temporal predictor of increased infection in Culex pipiens and Culex restuans mosquitoes, with cumulative high temperature differences being a key factor distinguishing years with higher mosquito infection and higher human illness rates from those with lower rates. Drier conditions in the spring followed by wetter conditions just prior to an increase in infection were factors in some but not all years. Overall, 80% of the weekly variation in mosquito infection was explained by prior weather conditions. Spatially, lower precipitation was the most important variable predicting stronger mosquito infection; precipitation and temperature alone could explain the pattern of spatial variability better than could other environmental variables (79% explained in the best model). Variables related to impervious surfaces and elevation differences were of modest importance in the spatial model. Conclusion Finely grained temporal and spatial patterns of precipitation and air temperature have a consistent and significant impact on the timing and location of increased mosquito infection in the northeastern Illinois study area. The use of local weather data at multiple monitoring locations and the integration of mosquito infection data from numerous sources across several years are important to the strength of the models presented. The other spatial environmental factors that tended to be important, including impervious surfaces and elevation measures, would mediate the effect of rainfall on soils and in urban catch basins. Changes in weather patterns with global climate change make it especially important to improve our ability to predict how inter-related local weather and environmental factors affect vectors and vector-borne disease risk. Local impact of temperature and precipitation on West Nile virus infection in Culex species mosquitoes in northeast Illinois, USA.

Authors

Ruiz, Marilyn O, Chaves, Luis F, Hamer, Gabriel L, Sun, Ting, Brown, William M, Walker, Edward D, Haramis, Linn, Goldberg, Tony L and Kitron, Uriel D

Year Published

2010

Publication

Parasites & Vectors

Locations
DOI

10.1186/1756-3305-3-19

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20302617

Evidence of vertical transmission of West Nile virus in field-collected mosquitoesUnlu, Isik2010

Evidence of vertical transmission of West Nile virus in field-collected mosquitoes

Keywords

West Nile virus;mosquitoes;vertical transmission, WNV

Abstract

Male and nulliparous female mosquitoes were surveyed for evidence of vertical WNV infection in East Baton Rouge Parish, Louisiana. Adult male mosquitoes collected by trapping and aspiration, and adult male and nulliparous female mosquitoes reared from field-collected larvae were tested. Adult male Culex spp., female Aedes albopictus (Skuse), and female Culex quinquifasciatus Say mosquitoes that were collected as larvae were test-positive for WNV RNA. Infectious WNV was detected using virus isolation in field-collected male Aedes triseriatus Say and Culex salinarius Coquillett; these data represent the first field evidence of vertical transmission of WNV in Ae. triseriatus and Cx. salinarius.

Authors

Unlu, Isik, Mackay, Andrew J., Roy, Alma, Yates, Matt M. and Foil, Lane D.

Year Published

2010

Publication

Journal of Vector Ecology

Locations
DOI

10.1111/j.1948-7134.2010.00064.x

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20618654

Genome-Based Microsatellite Development in the Culex pipiens Complex and Comparative Microsatellite Frequency with Aedes aegypti and Anopheles gambiaeHickner, Paul V.2010

Genome-Based Microsatellite Development in the Culex pipiens Complex and Comparative Microsatellite Frequency with Aedes aegypti and Anopheles gambiae

Keywords

WNV

Abstract

Mosquitoes in the Culex pipiens complex are among the most medically important vectors for human disease worldwide and include major vectors for lymphatic filariasis and West Nile virus transmission. However, detailed genetic studies in the complex are limited by the number of genetic markers available. Here, we describe methods for the rapid and efficient identification and development of single locus, highly polymorphic microsatellite markers for Cx. pipiens complex mosquitoes via in silico screening of the Cx. quinquefasciatus genome sequence.

Authors

Hickner, Paul V., deBruyn, Becky, Lovin, Diane D., Mori, Akio, Behura, Susanta K., Pinger, Robert and Severson, David W.

Year Published

2010

Publication

PLOS One

Locations
DOI

10.1371/journal.pone.0013062

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20927334

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Temperature has played a critical role in the spatiotemporal dynamics of West Nile virus transmission throughout California from its introduction in 2003 through establishment by 2009. We compared two novel mechanistic measures of transmission risk, the temperature-dependent ratio of virus extrinsic incubation period to the mosquito gonotrophic period (BT), and the fundamental reproductive rati...

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Culex pipiens L. (Diptera: Culicidae) and Culex restuans Theobald are the primary enzootic and bridge vectors of West Nile virus in the eastern United States north of 36° latitude. Recent studies of the natural history of these species have implicated catch basins and underground storm drain systems as important larval development sites in urban and suburban locales. Although the presence of la...

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Accurate data on West Nile virus (WNV) cases help guide public health education and control activities, and impact regional WNV blood product screening procedures. During an outbreak of WNV disease in Arizona, records from patients with meningitis or encephalitis were reviewed to determine the proportion tested for WNV. Of 60 patients identified with meningitis or encephalitis, 24 (40%) were te...

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