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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
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

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

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

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

NONTARGET EFFECTS OF THE MOSQUITO ADULTICIDE PYRETHRIN APPLIED AERIALLY DURING A WEST NILE VIRUS OUTBREAK IN AN URBAN CALIFORNIA ENVIRONMENTBOYCE, WALTER M.2007

NONTARGET EFFECTS OF THE MOSQUITO ADULTICIDE PYRETHRIN APPLIED AERIALLY DURING A WEST NILE VIRUS OUTBREAK IN AN URBAN CALIFORNIA ENVIRONMENT

Keywords

Ultra-low volume adulticide, nontarget mortality, pyrethrins, WNV

Abstract

In August 2006, a pyrethrin insecticide synergized with piperonyl butoxide (EverGreen® Crop Protection EC 60-6, McLaughlin Gormley King Company, Golden Valley, MN) was sprayed in ultra-low volumes over the city of Davis, CA, by the Sacramento–Yolo Mosquito and Vector Control District to control mosquitoes transmitting West Nile virus. Concurrently, we evaluated the impact of the insecticide on nontarget arthropods by 1) comparing mortality of treatment and control groups of sentinel arthropods, and 2) measuring the diversity and abundance of dead arthropods found on treatment and control tarps placed on the ground. We found no effect of spraying on nontarget sentinel species including dragonflies (Sympetrum corruptum), spiders (Argiope aurantia), butterflies (Colias eurytheme), and honeybees (Apis mellifera). In contrast, significantly higher diversity and numbers of nontarget arthropods were found on ground tarps placed in sprayed versus unsprayed areas. All of the dead nontarget species were small-bodied arthropods as opposed to the large-bodied sentinels that were not affected. The mortality of sentinel mosquitoes placed at the same sites as the nontarget sentinels and ground tarps ranged from 0% to 100%. Dead mosquitoes were not found on the ground tarps. We conclude that aerial spraying with pyrethrins had no impact on the large-bodied arthropods placed in the spray zone, but did have a measurable impact on a wide range of small-bodied organisms.

Authors

Reisen, William K., BOYCE, WALTER M., LAWLER, SHARON P., SCHULTZ, JENNIFER M., McCAULEY, SHANNON J., KIMSEY, LYNN S., NIEMELA, MICHAEL K. and NIELSEN, CARRIE F.

Year Published

2007

Publication

Journal of the American Mosquito Control Association

Locations
DOI

10.2987/8756-971X(2007)23[335:NEOTMA]2.0.CO;2

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/17939516

Surveillance for West Nile Virus and Vaccination of Free-Ranging Island Scrub-Jays ( Aphelocoma insularis ) on Santa Cruz Island, California BOYCE, WALTER M.2011

Surveillance for West Nile Virus and Vaccination of Free-Ranging Island Scrub-Jays ( Aphelocoma insularis ) on Santa Cruz Island, California

Keywords

WNV

Abstract

Abstract Transmission of West Nile virus (WNV) on mainland California poses an ongoing threat to the island scrub-jay (ISSJ, Aphelocoma insularis), a species that occurs only on Santa Cruz Island, California, and whose total population numbers 750 migrating and resident birds on the island from 2006 to 2009 indicated that WNV had not become established by the end of 2009. Several species of competent mosquito vectors were collected at very low abundance on the island, including the important mainland vectors Culex tarsalis and Culex quinquefasciatus. However, the island was generally cooler than areas of mainland California that experienced intense WNV transmission, and these lower temperatures may have reduced the likelihood of WNV becoming established because they do not support efficient virus replication in mosquitoes. A vaccination program was initiated in 2008 to create a rescue population of ISSJ that would be more likely to survive a catastrophic outbreak. To further that goal, we recommend managers vaccinate >100 ISSJ each year as part of ongoing research and monitoring efforts.

Authors

BOYCE, WALTER M., Vickers, Winston, Morrison, Scott A., Sillett, T. Scott, Caldwell, Luke, Wheeler, Sarah S., Barker, Christopher M., Cummings, Robert and Reisen, William K.

Year Published

2011

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2010.0171

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/21438695

Seasonal Patterns for Entomological Measures of Risk for Exposure to Culex Vectors and West Nile Virus in Relation to Human Disease Cases in Northeastern ColoradoBolling, Bethany G.2009

Seasonal Patterns for Entomological Measures of Risk for Exposure to Culex Vectors and West Nile Virus in Relation to Human Disease Cases in Northeastern Colorado

Keywords

Culex pipiens, Culex tarsalis, Colorado, seasonal risk, West Nile virus, WNV

Abstract

We examined seasonal patterns for entomological measures of risk for exposure to Culex vectors and West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in relation to human WNV disease cases in a five-county area of northeastern Colorado during 2006–2007. Studies along habitat/ elevation gradients in 2006 showed that the seasonal activity period is shortened and peak numbers occur later in the summer for Culex tarsalis Coquillett females in foothills-montane areas > 1,600 m compared with plains areas 1,600 m. The vector index for abundance of WNV-infected Cx. tarsalis females for the plains sites combined exceeded 0.50 from mid-July to mid-August, with at least one site exceeding 1.00 from early July to late August. Finally, we found that abundance of Cx. tarsalis females and the vector index for infected females were strongly associated with weekly numbers of WNV disease cases with onset 4–7 wk later (female abundance) or 1–2 wk later (vector index).

Authors

Bolling, Bethany G., Barker, Christopher M., Moore, Chester G., Pape, W. John and Eisen, Lars

Year Published

2009

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/033.046.0641

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19960707

ENTOMOLOGICAL STUDIES ALONG THE COLORADO FRONT RANGE DURING A PERIOD OF INTENSE WEST NILE VIRUS ACTIVITYBOLLING, B.G.2007

ENTOMOLOGICAL STUDIES ALONG THE COLORADO FRONT RANGE DURING A PERIOD OF INTENSE WEST NILE VIRUS ACTIVITY

Keywords

West Nile virus, vector ecology, Culex pipiens, Culex tarsalis, overwintering, WNV

Abstract

To better understand the ecology of West Nile virus transmission in Northern Colorado, field studies were conducted in Larimer and Weld counties from September 2003 through March 2005. During summer studies, 18,540 adult mosquitoes were collected using light traps and gravid traps. West Nile virus RNA was detected in 24 of the 2,140 mosquito pools tested throughout the study area in 2003 and 2004. Culex tarsalis had the highest minimum infection rate (MIR) in both 2003 (MIR  =  34.48) and in 2004 (MIR  =  8.74). During winter studies, 9,391 adult mosquitoes were collected by aspirator from various overwintering sites including bridges and storm drains. The most frequently collected species was Culex pipiens. West Nile virus was not detected in our overwintering collections. The relationship between spring adult emergence and temperature inside and outside overwintering sites is described. Species composition of collections as well as the spatial and temporal distribution of West Nile virus detections are presented.

Authors

BOLLING, B.G., MOORE, C.G., ANDERSON, S.L., BLAIR, C.D. and BEATY, B.J.

Year Published

2007

Publication

Journal of the American Mosquito Control Association

Locations
DOI

10.2987/8756-971X(2007)23[37:ESATCF]2.0.CO;2

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/17536366

Serologic Survey of Select Infectious Diseases in Coyotes and Raccoons in NebraskaBischof, Richard2005

Serologic Survey of Select Infectious Diseases in Coyotes and Raccoons in Nebraska

Keywords

Canine distemper virus, coyote, Francisella tularensis, Leptospira interrogans, Nebraska, raccoon, Rickettsia rickettsi, serology, West Nile virus, WNV

Abstract

To obtain data about select zoonotic and other infectious diseases in free-ranging predators in five ecoregions in Nebraska, sera were collected from 67 coyotes (Canis la-trans) and 63 raccoons (Procyon lotor) from November 2002 through January 2003. For coyotes, antibodies were detected against canine distemper virus (CDV, 61%), Francisella tularensis (32%), Rickettsia rickettsi (13%), and flaviviruses (48%). None of the coyote sera had antibodies to Borrelia burgdorferi, Brucella canis, or six serovars of Leptospira interrogans. Because serologic cross-reactivity exists among flaviviruses, 14 sera from flavivirus-positive coyotes were also tested for St. Louis encephalitis virus (SLE) antibodies and two (14%) were positive, suggesting that up to 48% of coyotes tested had antibodies against West Nile virus (WNV). For raccoons, antibodies were detected against CDV (33%), F. tularensis (38%), and three serovars of L. interrogans (11%).

Authors

Bischof, Richard and Rogers, Douglas G.

Year Published

2005

Publication

Journal of Wildlife Diseases

Locations
DOI

10.7589/0090-3558-41.4.787

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16456169

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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

by Hamer, S. A., Lehrer, E. and Magle, S. B.

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.

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