Small

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
Delinquent Mortgages, Neglected Swimming Pools, and West Nile Virus, CaliforniaReisen, William K.2008

Delinquent Mortgages, Neglected Swimming Pools, and West Nile Virus, California

Keywords

WNV

Abstract

Adjustable rate mortgages and the downturn in the California housing market caused a 300% increase in notices of delinquency in Bakersfield, Kern County. This led to large numbers of neglected swimming pools, which were associated with a 276% increase in the number of human West Nile virus cases during the summer of 2007.

Authors

Reisen, William K., Takahashi, Richard M., Carroll, Brian D. and Quiring, Rob

Year Published

2008

Publication

Emerging Infectious Diseases

Locations
DOI

10.3201/eid1411.080719

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/18976560

Persistent West Nile Virus Transmission and the Apparent Displacement St. Louis Encephalitis Virus in Southeastern California, 2003–2006Reisen, William K.2008

Persistent West Nile Virus Transmission and the Apparent Displacement St. Louis Encephalitis Virus in Southeastern California, 2003–2006

Keywords

West Nile virus, St. Louis encephalitis virus, western equine encephalomyelitis virus, Culex tarsalis, Culex pipiens quinquefasciatus, WNV

Abstract

West Nile virus (family Flaviviridae, genus Flavivirus, WNV) invaded the Colorado Desert biome of southern California during summer 2003 and seemed to displace previously endemic St. Louis encephalitis virus (family Flaviviridae, genus Flavivirus, SLEV, an antigenically similar Flavivirus in the Japanese encephalitis virus serocomplex). Western equine encephalomyelitis virus (family Togaviridae, genus Alphavirus, WEEV), an antigenically distinct Alphavirus, was detected during 2005 and 2006, indicating that conditions were suitable for encephalitis virus introduction and detection. Cross-protective “avian herd immunity” due to WNV infection possibly may have prevented SLEV reintroduction and/or amplification to detectable levels. During 2003–2006, WNV was consistently active at wetlands and agricultural habitats surrounding the Salton Sea where Culex tarsalis Coquillett served as the primary enzootic maintenance and amplification vector. Based on published laboratory infection studies and the current seroprevalence estimates, house sparrows, house finches, and several Ardeidae may have been important avian amplifying hosts in this region. Transmission efficiency may have been dampened by high infection rates in incompetent avian hosts, including Gamble’s quail, mourning doves, common ground doves, and domestic pigeons. Early season WNV amplification and dispersal from North Shore in the southeastern portion of the Coachella Valley resulted in sporadic WNV incursions into the urbanized Upper Valley near Palm Springs, where Culex pipiens quinquefasciatus Say was the primary enzootic and bridge vector. Although relatively few human cases were detected during the 2003–2006 period, all were concentrated in the Upper Valley and were associated with high human population density and WNV infection in peridomestic populations of Cx. p. quinquefasciatus. Intensive early mosquito control during 2006 seemed to interrupt and delay transmission, perhaps setting the stage for the future reintroduction of SLEV.

Authors

Reisen, William K., Fang, Ying, Lothrop, Hugh D., Wheeler, Sarah S., Kennsington, Marc, Gutierrez, Arturo, Garcia, Sandra and Lothrop, Branka

Year Published

2008

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/0022-2585(2008)45[494:PWNVTA]2.0.CO;2

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/18533445

Repeated West Nile Virus Epidemic Transmission in Kern County, California, 2004–2007Reisen, William K.2009

Repeated West Nile Virus Epidemic Transmission in Kern County, California, 2004–2007

Keywords

WNV

Abstract

West Nile virus (WNV) has remained epidemic in Kern County, CA, since its introduction in 2004 through 2007 when the human case annual incidence increased from 6-8 to 17 per 100,000, respectively. The 2007 increase in human infection was associated with contradicting surveillance indicators, including severe drought, warm spring but cool summer temperature anomalies, decreased rural and urban mosquito abundance but increased early season infection in urban Culex quinquefasciatus Say, moderate avian "herd immunity," and declines in the catch of competent (western scrub-jay and house finch) and noncompetent (California quail and mourning dove) avian species. The decline in these noncompetent avian hosts may have increased contact with competent avian hosts and perhaps humans. The marked increase in home foreclosures and associated neglected swimming pools increased urban mosquito production sites, most likely contributing to the urban mosquito population and the WNV outbreak within Bakersfield. Coalescing five surveillance indicators into a risk assessment score measured each half month provided 2- to 6-wk early warning for emergency planning and was followed consistently by the onset of human cases after reaching epidemic conditions. St. Louis encephalitis virus (SLEV) antibody was detected rarely in wild birds but not mosquitoes or sentinel chickens, indicating that previously infected birds were detected in Kern County, but SLEV reintroduction was not successful. In contrast, western equine encephalitis virus (WEEV) was detected during 3 of 5 yr in Culex tarsalis Coquillett, sentinel chickens, and wild birds, but failed to amplify to levels where tangential transmission was detected in Aedes mosquitoes or humans. A comparison of transmission patterns in Kern County to Coachella Valley in the southeastern desert of California showed the importance of mosquito phenology and spatial distribution, corvids, or other avian "super spreaders" and anthropogenic factors in WNV epidemiology.

Authors

Reisen, William K., Carroll, Brian D., Takahashi, Richard, Fang, Ying, Garcia, Sandra, Martinez, Vincent M. and Quiring, Rob

Year Published

2009

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/033.046.0118

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19198528

Role of Communally Nesting Ardeid Birds in the Epidemiology of West Nile Virus RevisitedReisen, William K.2009

Role of Communally Nesting Ardeid Birds in the Epidemiology of West Nile Virus Revisited

Keywords

WNV

Abstract

Although herons and egrets in the family Ardeidae frequently have been associated with viruses in the Japanese encephalitis virus serocomplex, communal nesting colonies do not appear to be a focus of early season and rapid amplification of West Nile virus (WNV) in California. Evidence for repeated WNV infection was found by testing living and dead nestlings collected under trees with mixed species ardeid colonies nesting above in an oak grove near the University of California arboretum in Davis and in a Eucalyptus grove at a rural farmstead. However, mosquito infection rates at both nesting sites were low and positive pools did not occur earlier than at comparison sites within the City of Davis or at the Yolo Bypass wetlands managed for rice production and waterfowl habitat. Black-crowned night herons (Nycticorax nycticorax) were the most abundant and frequently infected ardeid species, indicating that WNV may be an important cause of mortality among nestlings of this species.

Authors

Reisen, William K., Wheeler, Sarah, Armijos, M. Veronica, Fang, Ying, Garcia, Sandra, Kelley, Kara and Wright, Stan

Year Published

2009

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2008.0104

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19125659

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

Migratory Birds and the Dispersal of Arboviruses in CaliforniaReisen, W. K.2010

Migratory Birds and the Dispersal of Arboviruses in California

Keywords

WNV

Abstract

Each spring large numbers of neotropical migrants traversing the Pacific flyway pass through the Coachella Valley enroute to northern destinations, providing an opportunity to test the hypothesis that mosquito-borne encephalitis viruses are introduced annually into California by migratory birds. A total of 5,632 sera were collected from 43 species of migrants during spring (April-June), of which 34 (0.61%) comprised of 14 species tested positive by enzyme immunoassay; only 10 were confirmed by plaque reduction neutralization tests (PRNT). In addition, of 1,109 migrants comprised of 76 species that were reported dead by the public and necropsied, 126 (11%) were positive for West Nile virus (WNV) RNA; however, only three (0.7%) of 428 birds tested during the spring were positive. Limited experimental infection studies with WNV showed that Orange-crowned Warblers were highly susceptible and frequently died, whereas most Yellow Warblers survived. Our results indicated that birds entering California rarely exhibited a history of infection and that most birds probably became infected after entering California.

Authors

Reisen, W. K., Wheeler, S. S., Garcia, S. and Fang, Y.

Year Published

2010

Publication

American Journal of Tropical Medicine and Hygiene

Locations
DOI

10.4269/ajtmh.2010.10-0200

Efficacy of Resmethrin Aerosols Applied from the Road for Suppressing Culex Vectors of West Nile Virus Reddy, Michael R.2006

Efficacy of Resmethrin Aerosols Applied from the Road for Suppressing Culex Vectors of West Nile Virus

Keywords

WNV

Abstract

We determined whether aerosol applications of resmethrin, delivered from the road, suppress the reproductive activity of Culex pipiens pipiens and Cx. restuans mosquitoes in suburban sites located near Boston. Oviposition implies a prior blood-feeding event and hence a potential West Nile virus (WNV) transmission-related event. Droplet size, rate of delivery and meteorological conditions were monitored. The target populations proved to be fully susceptible to the insecticide that was used. The roads in the test sites generally gave adequate opportunity for insecticidal coverage. We found that the aerosol plume may have failed to contact the target mosquitoes and conclude that such insecticidal aerosols, delivered from the road, may not effectively reduce the force of transmission of WNV in our test sites.

Authors

Reddy, Michael R., Spielman, Andrew, Lepore, Timothy J., Henley, David, Kiszewski, Anthony E. and Reiter, Paul

Year Published

2006

Publication

Vector-Borne and Zoonotic Diseases

Locations
DOI

10.1089/vbz.2006.6.117

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16796509

Cerebrospinal fluid cytology in seasonal epidemic West Nile virus meningo-encephalitisRawal, Ajay2006

Cerebrospinal fluid cytology in seasonal epidemic West Nile virus meningo-encephalitis

Keywords

West Nile virus;cytology;cerebrospinal fluid;pleocytosis, WNV

Abstract

The incidence of West Nile Virus (WNV) infection has progressively increased in North America since the first epidemic in 1999. Formal scholarly documentation of cerebrospinal fluid (CSF) cytology changes in patients with WNV infection is limited. We report our experience with CSF cytospins from a population of consecutive patients with documented CSF WNV-specific IgM. Thirty-two patients (12 male, 20 female) with a median age of 52 yr (range, 19–88) diagnosed with WNV meningo-encephalitis were studied. Symptoms were present for a mean of 5 days (range, 1–14) prior to lumbar puncture. CSF proteins were elevated in 94% of patients (30/32) with a mean value of 79 mg/dl (range, 36–185). CSF glucose was normal to elevated in all cases. All cytomorphologically adequate samples demonstrated a pleocytosis with a mean of 156 cells/mm3 (range, 13–683). Nearly, all (26/28) patients showed increased CSF neutrophils- mean 43% (range, 1–83). Mean lymphocyte and monocyte fractions were 44% (range, 8–85) and 14% (range, 2–27), respectively. Three cases showed 1–4% plasma cells. Mean total leukocyte counts (TLC) (197 cells/mm3) and mean neutrophil fractions (50%) were greater in patients sampled within the first 3 days of symptoms than in those sampled beyond day 3 (mean TLC, 126 cells/mm3; mean neutrophil fraction, 37%). Relative lymphocyte proportions increased from a mean of 39 to 48% after 3 days of illness. WNV should be considered as a potential etiology of infectious CSF pleocytosis in the North American late summer and early fall seasons.

Authors

Rawal, Ajay, Gavin, Patrick J. and Sturgis, Charles D.

Year Published

2006

Publication

Diagnostic Cytopathology

Locations
DOI

10.1002/dc.20410

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/16511849

Evaluation of a New Formulation of Adulticide, Duet™, Against West Nile Virus Vector MosquitoesQualls, Whitney A.2010

Evaluation of a New Formulation of Adulticide, Duet™, Against West Nile Virus Vector Mosquitoes

Keywords

WNV

Abstract

DUET was evaluated against field-collected mosquito populations in St. John's County, FL, under laboratory and field conditions. Ten serial dilutions ranging from 22 to 2.2E-08 microg/ml of the product were tested against Aedes albopictus, Ae. taeniorhynchus, Culex quinquefasciatus, and Psorophora columbiae. At 0.0022 microg/ml, 100% mortality was recorded for all species except for Cx. quinquefasciatus. The 50% lethal concentration value for Cx. quinquefasciatus was 0.0029 microg/ml (CI = 0.00069 to 0.013). At the lowest dilution (2.2E-08 microg/ml) evaluated, Ae. albopictus, Ae. taeniorhynchus, and Ps. columbiae showed > 50% mortality. Ground ultralow-volume application of DUET resulted in overall average mortality of 87% of field-collected Cx. quinquefasciatus mosquitoes. There was a significant difference in mortality based on the distance of the caged mosquitoes (P < 0.05). However, mortality was > 70% at the farthest distance from the application (106 m).

Authors

Qualls, Whitney A. and Xue, Rui-De

Year Published

2010

Publication

Journal of the American Mosquito Control Association

Locations
DOI

10.2987/10-5993.1

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/20649133

Potential Vectors of West Nile Virus in a Semiarid Environment: Doña Ana County, New MexicoPitzer, Jimmy B.2009

Potential Vectors of West Nile Virus in a Semiarid Environment: Doña Ana County, New Mexico

Keywords

WNV

Abstract

The potential vectors of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in Doña Ana County, NM, were determined during 2004 and 2005. Trapping was conducted using Centers for Disease Control and Prevention miniature light-traps baited with dry ice, and gravid traps baited with a hay infusion. In addition, sentinel chickens were housed at four of the trapping locations to monitor WNV epizootic transmission. In total, 5,576 pools consisting of 115,797 female mosquitoes were tested for WNV by reverse transcription-polymerase chain reaction, of which 152 from 13 mosquito species representing six genera were positive. Culex tarsalis Coquillett, Culex quinquefasciatus Say, Culex erythrothorax Dyar, Aedes vexans (Meigan), and Psorophora columbiae (Dyar & Knab) accounted for 86% of all detections. Based on the frequency of WNV detection, our data indicate primary and secondary vector roles for Cx. tarsalis and Cx. quinquefasciatus, respectively, with Cx. erythrothorax, Ae. vexans, and Ps. columbiae as occasional vectors of WNV in Dofia Ana County. Other species testing positive for the virus included Aedes aegypti (L.), Anopheles franciscanus McCracken, Culex stigmatosoma Dyar, Culiseta inornata (Williston), Ochlerotatus dorsalis (Meigan), Ochlerotatus sollicitans (Walker), Ochlerotatus trivittatus (Coquillett), and Psorophora signipennis (Coquillett). Although they occurred after initial WNV detections in mosquitoes, in total, 21 seroconversions in sentinel chickens were detected during the study.

Authors

Pitzer, Jimmy B., Byford, Ronnie L., Vuong, Holly B., Steiner, Robert L., Creamer, Rebecca J. and Caccamise, Donald F.

Year Published

2009

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/033.046.0634

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19960700

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

Weather Variability Affects Abundance of Larval culex (diptera: Culicidae) in Storm Water Catch Basins in Suburban Chicago

by Gardner, Allison M., Hamer, Gabriel L., Hines, Alicia M., Newman, Christina M., Walker, Edward D. and Ruiz, Marilyn O.

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...

published 2012 in Journal of Medical Entomology


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