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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
Detection of West Nile Virus RNA in Mosquitoes and Identification of Mosquito Blood Meals Collected at Alligator Farms in LouisianaUnlu, Isik2010

Detection of West Nile Virus RNA in Mosquitoes and Identification of Mosquito Blood Meals Collected at Alligator Farms in Louisiana

Keywords

mosquitoes, Alligator mississippiensis, Culex quinquefasciatus, Culex nigripalpus, cytochrome B, WNV

Abstract

Since 2001, alligator farms in the United States have sustained substantial economic losses because of West Nile virus (WNV) outbreaks in American alligators (Alligator mississippiensis). Once an initial infection is introduced into captive alligators, WNV can spread among animals by contaminative transmission. Some outbreaks have been linked to feeding on infected meat or the introduction of infected hatchlings, but the initial source of WNV infection has been uncertain in other outbreaks. We conducted a study to identify species composition and presence of WNV in mosquito populations associated with alligator farms in Louisiana. A second objective of this study was to identify the origin of mosquito blood meals collected at commercial alligator farms. Mosquitoes were collected from 2004 to 2006, using Centers for Disease Control light traps, gravid traps, backpack aspirators, and resting boxes. We collected a total of 58,975 mosquitoes representing 24 species. WNV was detected in 41 pools of females from 11 mosquito species: Anopheles crucians, Anopheles quadrimaculatus, Coquillettidia perturbons, Culex coronator, Culex erraticus, Culex nigripalpus, Culex quinquefasciatus, Mansonia titillans, Aedes sollicitans, Psorophora columbiae, and Uranotaenia lowii. The blood meal origins of 213 field-collected mosquitoes were identified based on cytochrome B sequence identity. Alligator blood was detected in 21 mosquitoes representing six species of mosquitoes, including Cx. quinquefasciatus and Cx. nigripalpus. Our results showed that mosquitoes of species that are known to be competent vectors of WNV fed regularly on captive alligators. Therefore, mosquitoes probably are important in the role of transmission of WNV at alligator farms.

Authors

Unlu, Isik, Kramer, Wayne L., Roy, Alma F. and Foil, Lane D.

Year Published

2010

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/ME09087

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20695278

Effect of Holding Conditions on the Detection of West Nile Viral RNA by Reverse Transcriptase-Polymerase Chain Reaction from Mosquito (Diptera: Culicidae) PoolsTurell, Michael J.2002

Effect of Holding Conditions on the Detection of West Nile Viral RNA by Reverse Transcriptase-Polymerase Chain Reaction from Mosquito (Diptera: Culicidae) Pools

Keywords

WNV

Abstract

We evaluated the effect of holding temperature and time between mosquito death and processing mosquito pools for virus detection on our ability to detect West Nile (WN) viral RNA from pools of mosquitoes by reverse transcriptase-polymerase chain reaction (RT-PCR). Pools of 24 uninfected Culex pipiens L. mosquitoes were "spiked" with either a single Cx. pipiens that had been inoculated previously with WN virus or with an uninfected mosquito. These pools were held dry at 20, 4, -20, or -70 degrees C for selected time intervals before all mosquito pools were triturated in TRIzol LS reagent and processed for detection of WN viral RNA. While infectious virus virtually disappeared from pools maintained at 20 degrees C by 48 h after mosquito death, neither holding temperature (20 to -70 degrees C) nor holding period (up to 2 wk) affected detection of WN viral RNA by real-time RT-PCR. These findings suggest that we need not keep mosquitoes chilled to be able to detect WN viral RNA effectively by RT-PCR. This should enhance the feasibility of field-based WN virus surveillance programs where only detection of WN viral RNA is the objective and maintenance of a cold chain may not be possible.

Authors

Turell, Michael J., Spring, Alexandra R., Miller, Melissa K. and Cannon, Charles E.

Year Published

2002

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/0022-2585-39.1.1

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/11931239

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

Meteorologically Conditioned Time-Series Predictions of West Nile Virus Vector MosquitoesTrawinski, P.R.2008

Meteorologically Conditioned Time-Series Predictions of West Nile Virus Vector Mosquitoes

Keywords

WNV

Abstract

An empirical model to forecast West Nile virus mosquito vector populations is developed using time series analysis techniques. Specifically, multivariate seasonal autoregressive integrated moving average (SARIMA) models were developed for Aedes vexans and the combined group of Culex pipiens and Culex restuans in Erie County, New York. Weekly mosquito collections data were obtained for the four mosquito seasons from 2002 to 2005 from the Erie County Department of Health, Vector and Pest Control Program. Climate variables were tested for significance with cross-correlation analysis. Minimum temperature (Tmin), maximum temperature (Tmax), average temperature (Tave), precipitation (P), relative humidity (RH), and evapotranspiration (ET) were acquired from the Northeast Regional Climate Center (NRCC) at Cornell University. Weekly averages or sums of climate variables were calculated from the daily data. Other climate indexes were calculated and were tested for significance with the mosquito population data, including cooling degree days base 60 degrees (CDD_60), cooling degree days base 63 (CDD_63), cooling degree days base 65 (CDD_65), a ponding index (IP), and an interactive CDD_65-precipitation variable (CDD_65 × Pweek_4). Ae. vexans were adequately modeled with a (2,1,1)(1,1,0)52 SARIMA model. The combined group of Culex pipiens-restuans were modeled with a (0,1,1)(1,1,0)52 SARIMA model. The most significant meteorological variables for forecasting Aedes vexans abundance was the interactive CDD_65 × Pweek_4 variable at a lag of two weeks, ET × ET at a lag of five weeks, and CDD_65 × CDD_65 at a lag of seven weeks. The most significant predictive variables for the grouped Culex pipiens-restuans were CDD_63 × CDD_63 at a lag of zero weeks, CDD_63 at a lag of eight weeks, and the cumulative maximum ponding index (IPcum) at a lag of zero weeks.

Authors

Trawinski, P.R. and MacKay, D.S.

Year Published

2008

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2007.0202

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/18279008

Mosquito Host Selection Varies Seasonally with Host Availability and Mosquito DensityThiemann, Tara C.2011

Mosquito Host Selection Varies Seasonally with Host Availability and Mosquito Density

Keywords

WNV

Abstract

Host selection by vector mosquitoes is a critical component of virus proliferation, particularly for viruses such as West Nile (WNV) that are transmitted enzootically to a variety of avian hosts, and tangentially to dead-end hosts such as humans. Culex tarsalis is a principal vector of WNV in rural areas of western North America. Based on previous work, Cx. tarsalis utilizes a variety of avian and mammalian hosts and tends to feed more frequently on mammals in the late summer than during the rest of the year. To further explore this and other temporal changes in host selection, bloodfed females were collected at a rural farmstead and heron nesting site in Northern California from May 2008 through May 2009, and bloodmeal hosts identified using either a microsphere-based array or by sequencing of the mitochondrial cytochrome c oxidase I (COI) gene. Host composition during summer was dominated by four species of nesting Ardeidae. In addition, the site was populated with various passerine species as well as domestic farm animals and humans. When present, Cx. tarsalis fed predominantly (>80%) upon the ardeids, with Black-crowned Night-Herons, a highly competent WNV host, the most prevalent summer host. As the ardeids fledged and left the area and mosquito abundance increased in late summer, Cx. tarsalis feeding shifted to include more mammals, primarily cattle, and a high diversity of avian species. In the winter, Yellow-billed Magpies and House Sparrows were the predominant hosts, and Yellow-billed Magpies and American Robins were fed upon more frequently than expected given their relative abundance. These data demonstrated that host selection was likely based both on host availability and differences in utilization, that the shift of bloodfeeding to include more mammalian hosts was likely the result of both host availability and increased mosquito abundance, and that WNV-competent hosts were fed upon by Cx. tarsalis throughout the year.

Authors

Thiemann, Tara C., Wheeler, Sarah S., Barker, Christopher M. and Reisen, William K.

Year Published

2011

Publication

PLoS Neglected Tropical Diseases

Locations
DOI

10.1371/journal.pntd.0001452

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/22206038

Bloodmeal Host Congregation and Landscape Structure Impact the Estimation of Female Mosquito (Diptera: Culicidae) Abundance Using Dry Ice-Baited TrapsThiemann, Tara2011

Bloodmeal Host Congregation and Landscape Structure Impact the Estimation of Female Mosquito (Diptera: Culicidae) Abundance Using Dry Ice-Baited Traps

Keywords

Culex tarsalis, Anopheles freeborni, dry ice-baited traps, abundance, California, WNV

Abstract

Vegetation patterns and the presence of large numbers of nesting herons and egrets significantly altered the number of host-seeking Culex tarsalis Coquillett (Diptera: Culicidae) collected at dry ice-baited traps. The numbers of females collected per trap night at traps along the ecotone of Eucalyptus stands with and without a heron colony were always greater or equal to numbers collected at traps within or under canopy. No Cx. tarsalis were collected within or under Eucaplytus canopy during the peak heron nesting season, even though these birds frequently were infected with West Nile virus and large number of engorged females could be collected at resting boxes. These data indicate a diversion of host-seeking females from traps to nesting birds reducing sampling efficiency.

Authors

Thiemann, Tara, Nelms, Brittany and Reisen, William K.

Year Published

2011

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/ME10273

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/21661310

Year-round West Nile Virus Activity, Gulf Coast Region, Texas and LouisianaTesh, Robert B.2004

Year-round West Nile Virus Activity, Gulf Coast Region, Texas and Louisiana

Keywords

WNV

Abstract

West Nile virus (WNV) was detected in 11 dead birds and two mosquito pools collected in east Texas and southern Louisiana during surveillance studies in the winter of 2003 to 2004. These findings suggest that WNV is active throughout the year in this region of the United States.

Authors

Tesh, Robert B., Parsons, Ray, Siirin, Marina, Randle, Yvonne, Sargent, Chris, Guzman, Hilda, Wuithiranyagool, Taweesak, Higgs, Stephen, Vanlandingham, Dana L., Bala, Adil A., Haas, Keith and Zerinque, Brian

Year Published

2004

Publication

Emerging Infectious Diseases

Locations
DOI

10.3201/eid1009.040203

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/15498169

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

Fatal Encephalitis and Myocarditis in Young Domestic Geese ( Anser anser domesticus ) Caused by West Nile Virus Swayne, David E.2001

Fatal Encephalitis and Myocarditis in Young Domestic Geese ( Anser anser domesticus ) Caused by West Nile Virus

Keywords

WNV

Abstract

During 1999 and 2000, a disease outbreak of West Nile (WN) virus occurred in humans, horses, and wild and zoological birds in the northeastern USA. In our experiments, WN virus infection of young domestic geese (Anser anser domesticus) caused depression, weight loss, torticollis, opisthotonus, and death with accompanying encephalitis and myocarditis. Based on this experimental study and a field outbreak in Israel, WN virus is a disease threat to young goslings and viremia levels are potentially sufficient to infect mosquitoes and transmit WN virus to other animal species.

Authors

Swayne, David E., Beck, Joan R., Smith, Calandra S., Shieh, Wun-Ju and Zaki, Sharif R.

Year Published

2001

Publication

Emerging Infectious Diseases

Locations
DOI

10.3201/eid0704.010429

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/11585545

Increased Avian Diversity Is Associated with Lower Incidence of Human West Nile Infection: Observation of the Dilution EffectSwaddle, John P.2008

Increased Avian Diversity Is Associated with Lower Incidence of Human West Nile Infection: Observation of the Dilution Effect

Keywords

WNV

Abstract

Recent infectious disease models illustrate a suite of mechanisms that can result in lower incidence of disease in areas of higher disease host diversity–the ‘dilution effect’. These models are particularly applicable to human zoonoses, which are infectious diseases of wildlife that spill over into human populations. As many recent emerging infectious diseases are zoonoses, the mechanisms that underlie the ‘dilution effect’ are potentially widely applicable and could contribute greatly to our understanding of a suite of diseases. The dilution effect has largely been observed in the context of Lyme disease and the predictions of the underlying models have rarely been examined for other infectious diseases on a broad geographic scale. Here, we explored whether the dilution effect can be observed in the relationship between the incidence of human West Nile virus (WNV) infection and bird (host) diversity in the eastern US. We constructed a novel geospatial contrasts analysis that compares the small differences in avian diversity of neighboring US counties (where one county reported human cases of WNV and the other reported no cases) with associated between-county differences in human disease. We also controlled for confounding factors of climate, regional variation in mosquito vector type, urbanization, and human socioeconomic factors that are all likely to affect human disease incidence. We found there is lower incidence of human WNV in eastern US counties that have greater avian (viral host) diversity. This pattern exists when examining diversity-disease relationships both before WNV reached the US (in 1998) and once the epidemic was underway (in 2002). The robust disease-diversity relationships confirm that the dilution effect can be observed in another emerging infectious disease and illustrate an important ecosystem service provided by biodiversity, further supporting the growing view that protecting biodiversity should be considered in public health and safety plans.

Authors

Swaddle, John P. and Calos, Stavros E.

Year Published

2008

Publication

PLOS One

Locations
DOI

10.1371/journal.pone.0002488

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/18575599

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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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Wild Birds as Sentinels for Multiple Zoonotic Pathogens Along an Urban to Rural Gradient in Greater Chicago, Illinois

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Wild birds are important in the maintenance and transmission of many zoonotic pathogens. With increasing urbanization and the resulting emergence of zoonotic diseases, it is critical to understand the relationships among birds, vectors, zoonotic pathogens, and the urban landscape. Here, we use wild birds as sentinels across a gradient of urbanization to understand the relative risk of diseases ...

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Completeness of West Nile Virus Testing in Patients with Meningitis and Encephalitis During an Outbreak in Arizona, Usa

by WEBER, I. B., LINDSEY, N. P., BUNKO-PATTERSON, A. M., BRIGGS, G., WADLEIGH, T. J., SYLVESTER, T. L., LEVY, C., KOMATSU, K. K., LEHMAN, J. A., FISCHER, M. and STAPLES, J. E.

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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