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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
Remotely-Sensed Vegetation Indices Identify Mosquito Clusters of West Nile Virus Vectors in an Urban Landscape in the Northeastern United StatesBrown, Heidi2008

Remotely-Sensed Vegetation Indices Identify Mosquito Clusters of West Nile Virus Vectors in an Urban Landscape in the Northeastern United States

Keywords

WNV

Abstract

Heterogeneity in urban landscapes can influence the effectiveness of mosquito-borne disease control. We used remotely sensed vegetation indices to discriminate among mosquito habitats within a densely populated urban environment in New Haven, CT. ASTER derived vegetation indices were identified for 16 sites where adult mosquitoes were trapped over the summer of 2004. Canonical correlation analysis showed a significant relationship between the environmental variables (normalized difference vegetation index, disease/water stress index and distance to water) and four local West Nile virus competent vectors (Cx. pipiens, Cx. restuans, Cx. salinarius, and Ae. vexans) (0.93, P = 0.03) explaining 86% of the variance in the environmental and mosquito measures. Sites were clustered based on these remotely sensed environmental variables. Three clusters were identified which provide insight into the distribution of West Nile virus vectors in an urban area. Identification of habitat differences of mosquitoes within the urban landscape has important implications for understanding West Nile virus transmission and for control of vector-competent mosquito species.

Authors

Fish, Durland, Brown, Heidi, Diuk-Wasser, Maria and Andreadis, Theodore

Year Published

2008

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2007.0154

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/18452400

Ecologic Factors Associated with West Nile Virus Transmission, Northeastern United StatesBrown, Heidi E.2008

Ecologic Factors Associated with West Nile Virus Transmission, Northeastern United States

Keywords

WNV

Abstract

Since 1999, West Nile virus (WNV) disease has affected the northeastern United States. To describe the spatial epidemiology and identify risk factors for disease incidence, we analyzed 8 years (1999-2006) of county-based human WNV disease surveillance data. Among the 56.6 million residents in 8 northeastern states sharing primary enzootic vectors, we found 977 cases. We controlled for population density and potential bias from surveillance and spatial proximity. Analyses demonstrated significant spatial spreading from 1999 through 2004 (p0.75 cases/100,000 residents) than counties with the most (>70%) forest cover. These results quantify urbanization as a risk factor for WNV disease incidence and are consistent with knowledge of vector species in this area.

Authors

Brown, Heidi E., Childs, James E., Diuk-Wasser, Maria A. and Fish, Durland

Year Published

2008

Publication

Emerging Infectious Diseases

Locations
DOI

10.3201/eid1410.071396

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/18826816

The Effect of Spatial and Temporal Subsetting on Culex tarsalis Abundance Models—a Design for Sensible Reduction of Vector SurveillanceBrown, Heidi E.2011

The Effect of Spatial and Temporal Subsetting on Culex tarsalis Abundance Models—a Design for Sensible Reduction of Vector Surveillance

Keywords

WNV

Abstract

Early identification of increasing mosquito activity is critical to effective mosquito control, particularly when increasing host-seeking behavior may be associated with increased risk of mosquito-borne disease. In this paper, we analyzed the temporal abundance pattern of the West Nile Virus vector, Culex tarsalis, in Fort Collins, CO, using an autoregressive integrated moving average model. We determined that an autoregressive model order 5 with lagged minimum temperatures was best at describing the seasonal abundance of Cx. tarsalis. We then tested the effect of using both temporal and spatial subsets of the data to determine the effect of reduced sampling effort on abundance predictions. We found that, if reduced trapping is necessary due to limited resources, removal of the least productive 1/3 or 1/4 of the traps produced the least erroneous predictions of seasonality represented in the observed data. We show that this productivity-based subset scheme performs better than other sampling effort reductions in generating the best estimate of Cx. tarsalis abundance per trap-night.

Authors

Brown, Heidi E., Doyle, Michael S., Cox, Jonathan, Eisen, Rebecca J. and Nasci, Roger S.

Year Published

2011

Publication

Journal of the American Mosquito Control Association

Locations
DOI

10.2987/10-6077.1

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/21805843

Spatial Analysis of West Nile Virus: Rapid Risk Assessment of an Introduced Vector-Borne ZoonosisBrownstein, John S.2002

Spatial Analysis of West Nile Virus: Rapid Risk Assessment of an Introduced Vector-Borne Zoonosis

Keywords

WNV

Abstract

The distribution of human risk for West Nile virus was determined by spatial analysis of the initial case distribution for the New York City area in 1999 using remote sensing and geographic information system technologies. Cluster analysis revealed the presence of a statistically significant grouping of cases, which also indicates the area of probable virus introduction. Within the cluster, habitat suitability for potentially infective adult mosquitoes was measured by the amount of vegetation cover using satellite imagery. Logistic regression analysis revealed satellite-derived vegetation abundance to be significantly and positively associated with the presence of human cases. The logistic model was used to estimate the spatial distribution of human risk for West Nile virus throughout New York City. Accuracy of the resulting risk map was cross-validated using virus-positive mosquito sample sites. These new epidemiological methods aid in rapid entry point identification and spatial prediction of human risk of infection for introduced vector-borne pathogens.

Authors

Miller, James R., Brownstein, John S., Rosen, Hilary, Purdy, Dianne, Merlino, Mario, Mostashari, Farzad and Fish, Durland

Year Published

2002

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/15303660260613729

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/12737545

Winter Biology of Wetland Mosquitoes at a Focus of Eastern Equine Encephalomyelitis Virus Transmission in Alabama, USABurkett-Cadena, Nathan D.2011

Winter Biology of Wetland Mosquitoes at a Focus of Eastern Equine Encephalomyelitis Virus Transmission in Alabama, USA

Keywords

overwintering, mosquito, winter emergence, eastern equine encephalitis, WNV

Abstract

At temperate latitudes, vectors and pathogens must possess biological mechanisms for coping with cold temperatures and surviving from one transmission season to the next. Mosquitoes that overwinter in the adult stage have been proposed as winter maintenance hosts for certain arboviruses. In the cases of West Nile virus (family Flaviviridae, genus Flavivirus) and St. Louis encephalitis virus (family Flaviviridae, genus Flavivirus), discovery of infected overwintering females lends support to this hypothesis, but for other arboviruses, in particular Eastern equine encephalomyelitis virus (family Togaviridae, genus Alphavirus, EEEV), overwintering of the virus in mosquito hosts as not been demonstrated. In the current study, we collected overwintering mosquitoes from a focus of EEEV transmission in the southeastern United States to determine whether mosquitoes serve as winter maintenance hosts for EEEV and to document overwintering biologies of suspected vectors. No virus was detected via reverse transcription-polymerase chain reaction of >500 female mosquitoes collected during three winters. Investigation into the winter biologies indicated that Anopheles punctipennis (Say), Culex erraticus (Dyar & Knab), Culex peccator Dyar & Knab, and Uranotaenia sapphirina (Osten Sacken) overwinter as females. Females of these species were collected from hollow trees and emergence traps placed over ground holes. Southern magnolia, Magnolia grandiflora L., trees were preferred overwintering sites of culicine mosquitoes. Emergence from underground overwintering sites peaked in mid-March, when air temperatures reached 18–22°C, and the first bloodengorged females of Cx. erraticus and Cx. peccator were collected during this same period. Blood-fed Culex territans Walker females were collected as early as mid-February. This work provides insight into the overwintering biologies of suspected virus vectors at a site of active EEEV transmission and provides limited evidence against the hypothesis that EEEV persists through intertransmission periods in overwintering mosquitoes.

Authors

Burkett-Cadena, Nathan D., White, Gregory S., Eubanks, Micky D. and UNNASCH, THOMAS R.

Year Published

2011

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/ME10265

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/21936314

Host Reproductive Phenology Drives Seasonal Patterns of Host Use in MosquitoesBurkett-Cadena, Nathan D.2011

Host Reproductive Phenology Drives Seasonal Patterns of Host Use in Mosquitoes

Keywords

WNV

Abstract

Seasonal shifts in host use by mosquitoes from birds to mammals drive the timing and intensity of annual epidemics of mosquito-borne viruses, such as West Nile virus, in North America. The biological mechanism underlying these shifts has been a matter of debate, with hypotheses falling into two camps: (1) the shift is driven by changes in host abundance, or (2) the shift is driven by seasonal changes in the foraging behavior of mosquitoes. Here we explored the idea that seasonal changes in host use by mosquitoes are driven by temporal patterns of host reproduction. We investigated the relationship between seasonal patterns of host use by mosquitoes and host reproductive phenology by examining a seven-year dataset of blood meal identifications from a site in Tuskegee National Forest, Alabama USA and data on reproduction from the most commonly utilized endothermic (white-tailed deer, great blue heron, yellow-crowned night heron) and ectothermic (frogs) hosts. Our analysis revealed that feeding on each host peaked during periods of reproductive activity. Specifically, mosquitoes utilized herons in the spring and early summer, during periods of peak nest occupancy, whereas deer were fed upon most during the late summer and fall, the period corresponding to the peak in births for deer. For frogs, however, feeding on early- and late-season breeders paralleled peaks in male vocalization. We demonstrate for the first time that seasonal patterns of host use by mosquitoes track the reproductive phenology of the hosts. Peaks in relative mosquito feeding on each host during reproductive phases are likely the result of increased tolerance and decreased vigilance to attacking mosquitoes by nestlings and brooding adults (avian hosts), quiescent young (avian and mammalian hosts), and mate-seeking males (frogs).

Authors

Burkett-Cadena, Nathan D., McClure, Christopher J. W., Ligon, Russell A., Graham, Sean P., Guyer, Craig, Hill, Geoffrey E., Ditchkoff, Stephen S., Eubanks, Micky D., HASSAN, HASSAN K. and UNNASCH, THOMAS R.

Year Published

2011

Publication

PLOS One

Locations
DOI

10.1371/journal.pone.0017681

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/21408172

West Nile Virus in the New World: Appearance, Persistence, and Adaptation to a New Econiche—An Opportunity TakenCALISHER, CHARLES H.2000

West Nile Virus in the New World: Appearance, Persistence, and Adaptation to a New Econiche—An Opportunity Taken

Keywords

No keywords available

Abstract

No abstract available

Authors

CALISHER, CHARLES H.

Year Published

2000

Publication

Viral Immunology

Locations
    DOI

    10.1089/vim.2000.13.411

    A Method to Increase Efficiency in Testing Pooled Field-Collected MosquitoesChisenhall, Daniel M.2008

    A Method to Increase Efficiency in Testing Pooled Field-Collected Mosquitoes

    Keywords

    West Nile virus, mosquito pool, quantitative reverse transcriptase polymerase chain reaction, arbovirus testing, surveillance, WNV

    Abstract

    Testing field-caught mosquito collections can result in thousands of pools, and testing pools of 50 mosquitoes each can be both time consuming and cost prohibitive. Consequently, we have developed an alternative approach to testing mosquito pools for arboviruses, utilizing a superpool strategy. When mosquito samples are processed for extraction of viral RNA and subsequent virus testing via quantitative real-time polymerase chain reaction, each pool is tested individually. Using the method described here, 0.025 ml from each of 10 pools is combined into a superpool for RNA extraction and testing. When a virus-positive superpool sample is found, each of the original 10 pools that constitute this sample is tested individually in order to find the specific positive sample. By retesting the original samples after the initial superpool screen, we are still able to obtain reliable estimates for minimum infection rates or maximum likelihood estimations. To test this principle, we created controlled mosquito pools of known titer and subjected them to our superpool process. We were able to detect our entire range of laboratory-created pools as being West Nile virus (WNV) positive. In 2005, field surveillance efforts from our laboratory resulted in over 4,000 mosquito pools tested, with 8 resulting WNV-positive samples. We found that all of these field samples were detected as WNV positive using the superpool method and contained calculated virus titers from <0.1 to 4.1 log10 plaque-forming units/ml WNV, indicating that the limit of superpool detection of WNV is below this point. These results reveal that the superpool method could be accurately used to detect WNV in field-collected specimens.

    Authors

    Chisenhall, Daniel M., Vitek, Christopher J., Richards, Stephanie L. and Mores, Christopher N.

    Year Published

    2008

    Publication

    Journal of the American Mosquito Control Association

    Locations
    DOI

    10.2987/5671.1

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/18666541

    Parasites and Infectious Diseases of Greater Sage-Grouse.Christiansen, Thomas J.2011

    Parasites and Infectious Diseases of Greater Sage-Grouse.

    Keywords

    Centrocercus urophasianus, disease, greater sage-grouse, parasite, pathogen

    Abstract

    We report the parasites, infectious diseases, and noninfectious diseases related to toxicants found in Greater Sage-Grouse (Centrocercus urophasianus) across its range. Documentation of population-level effects is rare, although researchers have responded to the recent emergence of West Nile virus with rigorous efforts. West Nile virus shows greater virulence and potential population-level effects than any infectious agent detected in Greater Sage-Grouse to date. Research has demonstrated that (1) parasites and diseases can have population-level effects on grouse species; (2) new infectious diseases are emerging; and (3) habitat fragmentation is increasing the number of small, isolated populations of Greater Sage-Grouse. Natural resource management agencies need to develop additional research and systematic monitoring programs for evaluating the role of micro-and macro parasites, especially West Nile virus, infectious bronchitis and other corona viruses, avian retroviruses, Mycoplasma spp., and Eimeria spp. and associated enteric bacteria affecting sage-grouse populations.

    Authors

    Christiansen, Thomas J.; Tate, Cynthia M.

    Year Published

    2011

    Publication

    Studies in Avian Biology

    Locations
    DOI

    10.1525/california/9780520267114.001.0001

    Factors associated with mosquito pool positivity and the characterization of the West Nile viruses found within Louisiana during 2007Christofferson, Rebecca C2010

    Factors associated with mosquito pool positivity and the characterization of the West Nile viruses found within Louisiana during 2007

    Keywords

    WNV

    Abstract

    Background West Nile virus (WNV) is an arbovirus of public health importance in the genus Flavivirus, a group of positive sense RNA viruses. The NS3 gene has a high level of substitutions and is phylogenetically informative. Likewise, substitutions in the envelope region have been postulated to enable viruses to subvert immune responses. Analysis of these genes among isolates from positive mosquitoes collected in Louisiana illustrates the variation present in the regions and provides improved insight to a phylogenetic model. Employing a GIS eco-regionalization method, we hypothesized that WNV pool positivity was correlated with regional environmental characteristics. Further, we postulated that the phylogenetic delineations would be associated with variations in regional environmental conditions. Results Type of regional land cover was a significant effect (p < 0.0001) in the positive pool prediction, indicating that there is an ecological component driving WNV activity. Additionally, month of collection was significant (p < 0.0001); and thus there is a temporal component that contributes to the probability of getting a positive mosquito pool. All virus isolates are of the WNV 2002 lineage. There appears to be some diversity within both forested and wetland areas; and the possibility of a distinct clade in the wetland samples. Conclusions The phylogenetic analysis shows that there has been no reversion in Louisiana from the 2002 lineage which replaced the originally introduced strain. Our pool positivity model serves as a basis for future testing, and could direct mosquito control and surveillance efforts. Understanding how land cover and regional ecology effects mosquito pool positivity will greatly help focus mosquito abatement efforts. This would especially help in areas where abatement programs are limited due to either funding or man power. Moreover, understanding how regional environments drive phylogenetic variation will lead to a greater understanding of the interactions between ecology and disease prevalence.

    Authors

    Christofferson, Rebecca C, Roy, Alma F and Mores, Christopher N

    Year Published

    2010

    Publication

    Virology Journal

    Locations
    DOI

    10.1186/1743-422X-7-139

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/20579348

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