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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
West Nile Virus Infection Rates in Culex nigripalpus (Diptera: Culicidae) Do Not Reflect Transmission Rates in FloridaRutledge, C. Roxanne2003

West Nile Virus Infection Rates in Culex nigripalpus (Diptera: Culicidae) Do Not Reflect Transmission Rates in Florida

Keywords

West Nile virus, infection rate, field transmission, arbovirus, WNV

Abstract

We describe the first documented field transmission of West Nile (WN) virus by a North American mosquito. WN was first detected in northern Florida in 2001. An intensive mosquito trapping and surveillance program was conducted in this region for four nights to assess mosquito transmission of WN. Four mosquito traps, each with a single sentinel chicken, were placed at five different locations on each of four nights. A total of 11,948 mosquitoes was collected, and 14 mosquito pools were found to contain WN, giving a minimum infection rate between 1.08 and 7.54 per 1,000. Only one of the 80 sentinel chickens seroconverted to WN, demonstrating a single mosquito transmission event during the study and a mosquito transmission rate of between 0.8 and 1 per 1,000. Culex nigripalpus Theobald was responsible for WN transmission to the sentinel chicken, although both Cx. nigripalpus and Culex quinquefasciatus Say were found infected with WN. Mosquito transmission rates are reported in this study for the first time for a WN outbreak. This information is essential to determine risk of human and animal infection.

Authors

Lord, Cynthia C., Day, Jonathan F., Rutledge, C. Roxanne, Stark, Lillian M. and Tabachnick, Walter J.

Year Published

2003

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/0022-2585-40.3.253

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/12943101

West Nile virus infection in blood donors in the New York City area during the 2010 seasonal epidemicFrancis, Richard O.2012

West Nile virus infection in blood donors in the New York City area during the 2010 seasonal epidemic

Keywords

Immunoglobulin G, Humans, Epidemics: statistics & numerical data, Epidemics, Culicidae: virology, Culicidae, Blood Safety: statistics & numerical data, Blood Safety, Blood Donors: statistics & numerical data, Blood Donors, Antibodies, Viral: blood, Antibodies, Viral, Animals, Algorithms, Adult, West Nile virus: isolation & purification, West Nile virus: immunology, West Nile virus, West Nile Fever: epidemiology, West Nile Fever: blood, West Nile Fever, Seroepidemiologic Studies, Seasons, Retrospective Studies, Public Health: statistics & numerical data, Public Health, New York City: epidemiology, New York City, New Jersey: epidemiology, New Jersey, Incidence, Immunoglobulin M: blood, Immunoglobulin M, Immunoglobulin G: blood

Abstract

A uniform threshold strategy for converting from minipool (MP)-nucleic acid testing (NAT) to individual donation (ID)-NAT screening for acute West Nile virus (WNV) infection among blood donors is lacking. We report on WNV screening at the New York Blood Center during the 2010 seasonal WNV epidemic, the most severe epidemic in that state since the original outbreak in 1999.

Authors

Francis, Richard O., Strauss, Donna, Williams, Joan Dunn, Whaley, Shavonne and Shaz, Beth H.

Year Published

2012

Publication

Transfusion

Locations
DOI

10.1111/j.1537-2995.2012.03639.x

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/22486471

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

    WEST NILE VIRUS IN RAPTORS FROM VIRGINIA DURING 2003: CLINICAL, DIAGNOSTIC, AND EPIDEMIOLOGIC FINDINGSJoyner, Priscilla H.2006

    WEST NILE VIRUS IN RAPTORS FROM VIRGINIA DURING 2003: CLINICAL, DIAGNOSTIC, AND EPIDEMIOLOGIC FINDINGS

    Keywords

    Bubo virginianus, Buteo jamaicensis, epidemiology, great horned owl, hematology, raptors, red-tailed hawk, surveillance, West Nile virus, WNV

    Abstract

    Sixty-one birds of prey admitted to The Wildlife Center of Virginia (WCV; Waynesboro, Virginia, USA) from June to November 2003 were tested for West Nile virus (WNV) infection. Choanal and/or cloacal swabs were obtained and submitted to Virginia's Division of Consolidated Laboratory Services (Richmond, Virginia, USA) for analysis with real-time reverse transcriptase polymerase chain reaction (RT-PCR). Forty birds of prey were positive for WNV by RT-PCR. Five avian families and nine species of raptors were represented, with great horned owls (Bubo virginianus) and red-tailed hawks (Buteo jamaicensis) most frequently affected. Presenting clinical signs were consistent with previous reports of WNV infection in raptors; however, these differed between species. Of WNV positive birds, nonspecific signs of illness were the most common clinical findings, particularly in red-tailed hawks; signs included dehydration (n=20), emaciation (n=18), and depression (n=15). Neurologic abnormalities were frequently identified, especially in great horned owls, and included head tremors (n=17), ataxia (n=13), head incoordination (n=7), torticollis (n=3), nystagmus (n=3), and head tilt (n=3). Great horned owls exhibited anemia and leukocytosis with heterophilia, eosinophilia, and monocytosis consistent with chronic inflammation. Red-tailed hawks were anemic with a heterophilic leukocytosis and regenerative left shift. The majority of WNV cases occurred during August and September; there was a marked increase in the number of raptors admittedto WCV during these months followed by a marked decrease during October, November, and December. This pattern differed from mean monthly admissions during the previous 10 years and suggests a negative impact on local raptor populations. The effects of WNV on avian populations are largely unknown; however, because of their ecological importance, further investigation of the effects of WNV on raptor populations is warranted.

    Authors

    Joyner, Priscilla H., Kelly, Sean, Shreve, Allison A., Snead, Sarah E., Sleeman, Jonathan M. and Pettit, Denise A.

    Year Published

    2006

    Publication

    Journal of Wildlife Diseases

    Locations
    DOI

    10.7589/0090-3558-42.2.335

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/16870856

    West Nile Virus in Host-Seeking Mosquitoes within a Residential Neighborhood in Grand Forks, North DakotaBell, Jeffrey A.2005

    West Nile Virus in Host-Seeking Mosquitoes within a Residential Neighborhood in Grand Forks, North Dakota

    Keywords

    WNV

    Abstract

    West Nile virus (WNV) was first recovered in North Dakota near the city of Grand Forks in June 2002. During 2002, 2003, and 2004, we collected mosquitoes from Grand Forks using Mosquito Magnet™ traps and tested them for WNV. The seasonal abundance, species composition, and reproductive status of female mosquitoes were correlated with local environmental temperature and state surveillance data on WNV to determine the factors affecting local transmission of WNV. Over 90% of the mosquitoes collected were Aedes vexans, Ochlerotatus dorsalis, and Culex tarsalis, but WNV was detected only in Cx. tarsalis. Average summertime temperatures and relative abundance of mosquitoes were highest in 2002 but no WNV-positive mosquitoes were detected until the following summer. In 2003, nulliparous Cx. tarsalis appeared in mid-June (first summer brood), and parous Cx. tarsalis appeared in mid-July. The first WNV-positive pool occurred 21 July, and minimum daily infections rates increased thereafter until 27 August. The minimum infection rate (MIR) for Cx. tarsalis during the season was 5.7 infected mosquitoes per 1,000 tested, with the highest infection rates occurring at the end of the season as Cx. tarsalis populations started to decline. Mid-to-late August was identified as the period of highest risk for being bitten by a WNV-infected mosquito in Grand Forks during 2003. In 2004, viral activity in Grand Forks was low, due to very cool temperatures throughout the summer. To examine the genetic diversity of the 2003 WNV isolates from Grand Forks, we sequenced a 366-nucleotide region of the capsid and premembrane gene. Thirteen (46%) of the 28 WNV isolates contained at least one nucleotide substitution when compared to the homologous region of the progenitor WN NY-99 strain, and seven of these 13 substitutions coded for amino acid changes. Thus, WNV is established in North Dakota, it appears to be evolving and it is vectored primarily by Cx. tarsalis. Vector-Borne Zoonotic Dis. 5, 373–382.

    Authors

    Bell, Jeffrey A., Mickelson, Nathan J. and Vaughan, Jefferson A.

    Year Published

    2005

    Publication

    Vector-Borne and Zoonotic Diseases

    Locations
    DOI

    10.1089/vbz.2005.5.373

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/16417433

    West Nile Virus in CaliforniaReisen, William2004

    West Nile Virus in California

    Keywords

    WNV

    Abstract

    West Nile virus (WNV) was first detected in California during July 2003 by isolation from a pool of Culex tarsalis collected near El Centro, Imperial County. WNV then amplified and dispersed in Imperial and Coachella Valleys, where it was tracked by isolation from pools of Cx. tarsalis, seroconversions in sentinel chickens, and seroprevalence in free-ranging birds. WNV then dispersed to the city of Riverside, Riverside County, and to the Whittier Dam area of Los Angeles County, where it was detected in dead birds and pools of Cx. pipiens quinquefasciatus. By October, WNV was detected in dead birds collected from riparian corridors in Los Angeles, west to Long Beach, and through inland valleys south from Riverside and to San Diego County. WNV was reported concurrently from Arizona in mid-August but not from Baja, Mexico, until mid-November. Possible mechanisms for virus introduction, amplification, and dispersal are discussed.

    Authors

    Reisen, William, Lothrop, Hugh, Chiles, Robert, Madon, Minoo, Cossen, Cynthia, Woods, Leslie, Husted, Stan, Kramer, Vicki and Edman, John

    Year Published

    2004

    Publication

    Emerging Infectious Diseases

    Locations
    DOI

    10.3201/eid1008.040077

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/15496236

    West Nile Virus from Female and Male Mosquitoes (Diptera: Culicidae) in Subterranean, Ground, and Canopy Habitats in ConnecticutAnderson, John F.2006

    West Nile Virus from Female and Male Mosquitoes (Diptera: Culicidae) in Subterranean, Ground, and Canopy Habitats in Connecticut

    Keywords

    West Nile virus, Culex restuans, Culex salinarius, Aedes vexans, Culex pipiens, WNV

    Abstract

    In total, 93,532 female mosquitoes (Diptera: Culicidae) were captured in traps placed in subterranean (catch basin), ground (≈ 1.5 m above ground), and canopy (≈7.0 m above ground) habitats in Stamford and Stratford, CT, during 2003–2005. Culex pipiens L. was the most abundant (64.8%) of the 31 species identified. Significantly greater numbers of Cx. pipiens were captured in canopy-placed mosquito magnet experimental traps, and significantly greater numbers were collected in catch basin-placed (Centers for Disease Control) CDC traps than in CDC traps placed elsewhere. Culex restuans Theobald was captured in significantly greater numbers in traps placed in catch basins. Aedes vexans (Meigen), Aedes cinereus Meigen, and Aedes cantator (Coquillett) were significantly more abundant in ground traps. In total, 429 isolations of West Nile virus (WNV) were made from seven species of mosquitoes from late June through the end of October during 2003 through 2005. Three hundred ninety-eight (92.8%) isolates were from Cx. pipiens. Others were from Cx. restuans (n = 16), Culex salinarius Coquillett (n = 5), Ae. vexans (n = 4), Ae. cantator (n = 3), Aedes triseriatus (Say) (n = 2), and Ae. cinereus (n = 1). Multiple isolates from Cx. pipiens were made each week, primarily during the later part of July through the end of September. Weekly minimum infection rates (MIRs) were lower in 2004 (highest weekly MIR = 7.1) when no human cases were reported in Connecticut in comparison with 2003 and 2005 (highest weekly MIR = 83.9) when human cases were documented. Frequencies of infected pools were significantly higher in Cx. pipiens captured in traps in the canopy and significantly higher in catch basin placed traps than in traps at ground level. The physiological age structure of Cx. pipiens captured in the canopy was significantly different from that of Cx. pipiens collected in catch basins. Invariably, Cx. pipiens captured in the canopy were nulliparous or parous with ovaries in Christophers’ stage 2, whereas 58.7% of the females captured in catch basins possessed ovaries filled with mature oocytes in Christophers’ stage 5. Our results suggest that females in the canopy are seeking hosts, and after digestion of the bloodmeal and development of mature oocytes, they descend to catch basins for shelter and deposition of eggs. WNV was isolated from three, one, and two pools of male Cx. pipiens captured in catch basin-, ground-, and canopy-placed traps, respectively, and from six nulliparous Cx. pipiens females collected in the canopy. Weekly MIR ranged from 1.2 to 31.1 per 1,000 male specimens. These data show that mosquitoes become infected by means other than by blood feeding, possibly by transovarial transmission. The placement of traps in tree canopies and in catch basins can be used to augment current practices of placement of traps near the ground for surveillance of mosquitoes infected with WNV and for studies of the ecology of WNV.

    Authors

    Andreadis, Theodore G., Anderson, John F., Vossbrinck, Charles R., Main, Andy J. and Ferrandino, Francis J.

    Year Published

    2006

    Publication

    Journal of Medical Entomology

    Locations
    DOI

    10.1603/0022-2585(2006)43[1010:WNVFFA]2.0.CO;2

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/17017241

    West Nile Virus Epidemics in North America Are Driven by Shifts in Mosquito Feeding BehaviorKilpatrick, A. Marm2006

    West Nile Virus Epidemics in North America Are Driven by Shifts in Mosquito Feeding Behavior

    Keywords

    WNV

    Abstract

    West Nile virus (WNV) has caused repeated large-scale human epidemics in North America since it was first detected in 1999 and is now the dominant vector-borne disease in this continent. Understanding the factors that determine the intensity of the spillover of this zoonotic pathogen from birds to humans (via mosquitoes) is a prerequisite for predicting and preventing human epidemics. We integrated mosquito feeding behavior with data on the population dynamics and WNV epidemiology of mosquitoes, birds, and humans. We show that Culex pipiens, the dominant enzootic (bird-to-bird) and bridge (bird-to-human) vector of WNV in urbanized areas in the northeast and north-central United States, shifted its feeding preferences from birds to humans by 7-fold during late summer and early fall, coinciding with the dispersal of its preferred host (American robins, Turdus migratorius) and the rise in human WNV infections. We also show that feeding shifts in Cx. tarsalis amplify human WNV epidemics in Colorado and California and occur during periods of robin dispersal and migration. Our results provide a direct explanation for the timing and intensity of human WNV epidemics. Shifts in feeding from competent avian hosts early in an epidemic to incompetent humans after mosquito infection prevalences are high result in synergistic effects that greatly amplify the number of human infections of this and other pathogens. Our results underscore the dramatic effects of vector behavior in driving the transmission of zoonotic pathogens to humans.

    Authors

    Kramer, Laura D., Kilpatrick, A. Marm, Jones, Matthew J., Marra, Peter P. and Daszak, Peter

    Year Published

    2006

    Publication

    PLoS Biology

    Locations
    DOI

    10.1371/journal.pbio.0040082

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/16494532

    West Nile Virus Emergence and Persistence in Los Angeles, California, 2003-2008Kwan, J. L.2010

    West Nile Virus Emergence and Persistence in Los Angeles, California, 2003-2008

    Keywords

    WNV

    Abstract

    West Nile virus (WNV) invaded Los Angeles in September 2003, and during the subsequent five-year period followed a pattern of amplification, subsidence, and resurgence. Enzootic transmission was tracked by abundance and infection incidence in Culex pipiens quinquefasciatus and Cx. tarsalis and by seroprevalence in peridomestic passerine birds, infection in dead birds, and seroconversions in sentinel chickens. Culex p. quinquefasciatus served as the primary vector of WNV, with gravid traps serving as the best sampling method and the most consistent indicator of viral activity. Spatial scan statistics applied to mosquito infection and positive dead bird data delimited three major clusters of WNV transmission, with introduction occurring in the Los Angeles Basin, and amplification and dispersal events carrying transmission to the San Fernando and Santa Clarita valleys. Los Angeles experienced major epidemics in 2004 and 2008, providing a unique opportunity to investigate specific patterns of enzootic amplification preceding epidemics.

    Authors

    Kwan, J. L., Kluh, S., Madon, M. B. and Reisen, W. K.

    Year Published

    2010

    Publication

    American Journal of Tropical Medicine and Hygiene

    Locations
    DOI

    10.4269/ajtmh.2010.10-0076

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/20682890

    West Nile Virus Detection in Kidney, Cloacal, and Nasopharyngeal SpecimensOhajuruka, Ojimadu A.2005

    West Nile Virus Detection in Kidney, Cloacal, and Nasopharyngeal Specimens

    Keywords

    WNV

    Abstract

    We compared kidney tissue samples and cloacal and nasopharyngeal swab samples from field-collected dead crows and blue jays for West Nile virus surveillance. Compared to tissue samples, 35% more swab samples were false negative. Swab samples were usually positive only when the corresponding tissue sample was strongly positive.

    Authors

    Ohajuruka, Ojimadu A., Berry, Richard L., Grimes, Sheila and Farkas, Susanne

    Year Published

    2005

    Publication

    Emerging Infectious Diseases

    Locations
    DOI

    10.3201/eid1209.050016

    Additional Information:

    http://www.ncbi.nlm.nih.gov/pubmed/16229775

    Recent Articles

    Effects of Temperature on Emergence and Seasonality of West Nile Virus in California

    by Hartley, D. M., Barker, C. M., Le Menach, A., Niu, T., Gaff, H. D. and Reisen, W. K.

    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...

    published 2012 in American Journal of Tropical Medicine and Hygiene

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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 ...

    published 2012 in Zoonoses and Public Health

    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...

    published 2012 in Epidemiology and Infection