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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
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

Environmental risk factors associated with West Nile virus clinical disease in Florida horsesRIOS, L. M. V.2009

Environmental risk factors associated with West Nile virus clinical disease in Florida horses

Keywords

WNV

Abstract

The objective of this study was to examine the extrinsic risk factors of West Nile virus (WNV) clinical disease in Florida horses as established from confirmed and negative horses tested within the state from 2001 to 2003. An Arboviral Case Information Form (ACF) was submitted by a referring veterinarian at the time of testing to the Florida Department of Agriculture and Consumer Services on every horse suspected of a viral encephalitis in Florida. A follow-up survey that focused on arbovirus prevention and farm ecology was created and mailed to the owner of each tested horse. Data from the follow-up survey indicated peak WNV prevalence in the late summer months in Florida. Quarter horses were the most commonly affected breed. The WNV vaccine was highly protective and natural water on the property also had a protective association. Factors that increased the risk of WNV to horses were the use of fans and a stable construction of solid wood or cement. Some risk indicators were dead birds on the property and other ill animals on the property. Data from this retrospective study have helped identify factors associated with WNV transmission in equines in Florida. Horses that have not been vaccinated and show clinical signs of arboviral infection from June to November should be tested for WNV. Horses that have been vaccinated and show clinical signs should be tested when the vaccination was administered within 1 month or greater than 6 months prior to the onset of clinical symptoms associated with WN infection.

Authors

RIOS, L. M. V., SHEU, J.-J., DAY, J. F., MARUNIAK, J. E., SEINO, K., ZARETSKY, H. and LONG, M. T.

Year Published

2009

Publication

Medical and Veterinary Entomology

Locations
DOI

10.1111/j.1365-2915.2009.00821.x

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19941601

Severe Winter Freezes Enhance St. Louis Encephalitis Virus Amplification and Epidemic Transmission in Peninsular FloridaDay, Jonathan F.2009

Severe Winter Freezes Enhance St. Louis Encephalitis Virus Amplification and Epidemic Transmission in Peninsular Florida

Keywords

WNV

Abstract

Mosquito-borne arboviral epidemics tend to strike without warning. The driving force for these epidemics is a combination of biotic (vector, amplification host, and virus) and abiotic (meteorological conditions, especially rainfall and temperature) factors. Abiotic factors that facilitate the synchronization and interaction of vector and amplification host populations favor epidemic amplification and transmission. In Florida, epidemics of St. Louis encephalitis (SLE) virus (family Flaviviridae, genus Flavivirus, SLEV) have been preceded by major freezes one or two winters before the onset of human cases. Here, we analyze the relationship between severe winter freezes and epidemic SLEV transmission in peninsular Florida and show that there is a significant relationship between the transmission of SLEV and these severe freezes. We propose that by killing cold-sensitive understory vegetation in the mid-peninsular region of Florida, freezes enhance the reproductive success of ground-feeding avian amplification hosts, especially mourning doves and common grackles. In conjunction with other appropriate environmental signals, increased avian reproductive success may enhance SLEV and West Nile (WN) virus amplification and result in SLE and WN epidemics during years when all of the biological cycles are properly synchronized. The knowledge that winter freezes in Florida may enhance the amplification and epidemic transmission of SLE and WN viruses facilitates arboviral tracking and prediction of human risk of SLE and WN infection during the transmission season.

Authors

Day, Jonathan F. and Shaman, Jeffrey

Year Published

2009

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/033.046.0638

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19960704

Relationship Between Distance From Major Larval Habitats and Abundance of Adult Mosquitoes in Semiarid Plains Landscapes in ColoradoBarker, Christopher M.2009

Relationship Between Distance From Major Larval Habitats and Abundance of Adult Mosquitoes in Semiarid Plains Landscapes in Colorado

Keywords

WNV

Abstract

We examined the relationship between distance from major larval habitats and abundance of adult mosquitoes in the semiarid plains landscape characteristic of eastern Colorado. Mosquito collection was conducted from late June to early August 2007 and included trap locations at distances ranging from <10 m up to 20-150 m and 160-373 m from three major larval habitats: one area along a river corridor and two small reservoirs. The study yielded 65,140 mosquitoes of 14 species, and five species were sufficiently abundant to be included in statistical analyses: Aedes vexans (Meigen), Culex tarsalis Coquillett, Ochlerotatus dorsalis (Meigen) (=Ae. dorsalis), Ochlerotatus melanimon (Dyar) (=Ae. melanimon), and Culex pipiens L. Distance to nearest major larval habitat was not strongly related to Culex abundance within the approximately = 400-m range from larval habitats examined in this study. Abundance of Ae. vexans declined significantly with distance from the larval habitat, whereas abundance was significantly higher in the 20-150- and 160-373-m classes compared with areas within 10 m of the larval habitat for both Ochlerotatus species. Except for Ae. vexans, however, we did not find monotonic increasing or decreasing abundance trends associated with distance from larval habitats for the 400-m range examined. This, combined with a finding that fine-scale habitat heterogeneity influenced abundance for most of the mosquitoes examined, underscores the importance of considering not only distance from larval habitat but also fine-scale habitat heterogeneity to understand how important nuisance-biters and West Nile virus (family Flaviviridae, genus Flavivirus, WNV) vectors use the landscape. We also discuss how these results relate to previous studies from western North America and explore their relevance to operational implementation of adulticides to suppress mosquito vectors during WNV disease outbreaks in the Great Plains.

Authors

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

Year Published

2009

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/033.046.0606

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19960672

Field Efficacy of BG-Sentinel and Industry-Standard Traps for Aedes albopictus (Diptera: Culicidae) and West Nile Virus SurveillanceFarajollahi, Ary2009

Field Efficacy of BG-Sentinel and Industry-Standard Traps for Aedes albopictus (Diptera: Culicidae) and West Nile Virus Surveillance

Keywords

WNV

Abstract

Standard surveillance traps in North America for adult Aedes albopictus (Skuse) (Diptera: Culicidae), an invasive mosquito with public health implications, are currently ineffective. We compared the efficacy of the BG-Sentinel trap (BGS) with and without lures (BG-lure, octenol, and CO2), the Centers for Disease Control and Prevention light trap (CDC) with and without lures, and the gravid trap (GT) for Ae. albopictus collection in two urban sites in New Jersey. The BGS with or without lures collected more Ae. albopictus compared with other trap configurations and was more specific for Ae. albopictus. In Camden County, the BGS with lures collected three times more Ae. albopictus than the CDC (with CO2 only) and five times more than the GT. In Mercer County, BGS with lures collected the most mosquitoes, with 3 times more Ae. albopictus than the CDC with all lures and 50 times more than the GT. The BGS collected more male Ae. albopictus than other traps in both counties, providing further population monitoring. The GT and BGS provided a relative measure of the enzootic activity of West Nile virus in Culex spp. and the potential epidemic activity of WNV in Ae. albopictus. The BGS provides effective chemical and visual cues for host-seeking Ae. albopictus and should be used as a part of existing surveillance programs and new initiatives targeting this mosquito.

Authors

Farajollahi, Ary, Kesavaraju, Banugopan, Price, Dana C., WILLIAMS, GREGORY M., Healy, Sean P., Gaugler, Randy and Nelder, Mark P.

Year Published

2009

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/033.046.0426

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19645298

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

Rapid Assessment of Mosquitoes and Arbovirus Activity after Floods in Southeastern Kansas, 2007Harrison, Bruce A.2009

Rapid Assessment of Mosquitoes and Arbovirus Activity after Floods in Southeastern Kansas, 2007

Keywords

WNV

Abstract

A rapid assessment was conducted in July-August 2007 to determine the impact of heavy rains and early summer floods on the mosquitoes and arbovirus activity in 4 southeastern Kansas counties. During 10 days and nights of collections using different types and styles of mosquito traps, a total of 10,512 adult female mosquitoes representing 29 species were collected, including a new species record for Kansas (Psorophora mathesoni). High numbers of Aedes albopictus were collected. Over 4,000 specimens of 4 Culex species in 235 species-specific pools were tested for the presence of West Nile, St. Louis, and western equine encephalitis viruses. Thirty pools representing 3 Culex species were positive for West Nile virus (WNV). No other arboviruses were detected in the samples. Infection rates of WNV in Culex pipiens complex in 2 counties (10.7/1,000 to 22.6/1,000) and in Culex salinarius in 1 county (6.0/1,000) were sufficiently high to increase the risk of transmission to humans. The infection rate of WNV in Culex erraticus was 1.9/1,000 in one county. Two focal hot spots of intense WNV transmission were identified in Montgomery and Wilson counties, where infection rates in Cx. pipiens complex were 26/ 1,000 and 19.9/1,000, respectively. Despite confirmed evidence of WNV activity in the area, there was no increase in human cases of arboviral disease documented in the 4 counties for the remainder of 2007.

Authors

Harrison, Bruce A., Whitt, Parker B., Roberts, Lesa F., Lehman, Jennifer A., Lindsey, Nicole P., Nasci, Roger S. and Hansen, Gail R.

Year Published

2009

Publication

Journal of the American Mosquito Control Association

Locations
DOI

10.2987/08-5754.1

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19852215

Growth and Survival of Invasive Aedes albopictus Larvae on Diospyros virginiana LeavesKesavaraju, Banugopan2009

Growth and Survival of Invasive Aedes albopictus Larvae on Diospyros virginiana Leaves

Keywords

Aedes albopictus, persimmon, detritus, WNV

Abstract

Studies on the interactions of exotic species with their invaded environment are imperative in understanding their invasion biology. Larvae of container mosquitoes such as the invasive Aedes albopictus (Skuse) feed on microorganisms that subsist on allochthonous inputs like leaves. Ae. albopictus are vectors for many diseases including West Nile virus and are rapidly expanding their distribution in the United States. We tested the larval performance of Ae. albopictus at different larval densities in maple, oak, American elm, and persimmon. Survival was significantly lower and days to pupation were significantly higher with persimmon leaves compared with all others. In a follow-up experiment, we compared the performance of Ae. albopictus in different amounts of oak and persimmon and different ratios of persimmon + oak. The linear model for the growth rate (defined by larval head width) showed a positive slope as the amount of oak leaves increased in oak treatment, but there was no significant slope for persimmon. In the persimmon + oak combination, as the ratio of persimmon to oak increased, the growth rates of the larvae decreased. Lack of a significant slope for survival rate in combination with the results from the growth rate indicated that persimmon was a poor nutritional resource for Ae. albopictus.

Authors

Kesavaraju, Banugopan, Afify, Ali and Gaugler, Randy

Year Published

2009

Publication

Journal of Medical Entomology

Locations
DOI

10.1603/033.046.0308

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19496414

Avian Host-Selection by Culex pipiens in Experimental TrialsSimpson, Jennifer E.2009

Avian Host-Selection by Culex pipiens in Experimental Trials

Keywords

WNV

Abstract

Evidence from field studies suggests that Culex pipiens, the primary mosquito vector of West Nile virus (WNV) in the northeastern and north central United States, feeds preferentially on American robins (Turdus migratorius). To determine the contribution of innate preferences to observed preference patterns in the field, we conducted host preference trials with a known number of adult female C. pipiens in outdoor cages comparing the relative attractiveness of American robins with two common sympatric bird species, European starling, Sternus vulgaris and house sparrow, Passer domesticus. Host seeking C. pipiens were three times more likely to enter robin-baited traps when with the alternate host was a European starling (n = 4 trials; OR = 3.06; CI [1.42-6.46]) and almost twice more likely when the alternative was a house sparrow (n = 8 trials; OR = 1.80; CI = [1.22-2.90]). There was no difference in the probability of trap entry when two robins were offered (n = 8 trials). Logistic regression analysis determined that the age, sex and weight of the birds, the date of the trial, starting-time, temperature, humidity, wind-speed and age of the mosquitoes had no effect on the probability of a choosing a robin over an alternate bird. Findings indicate that preferential feeding by C. pipiens mosquitoes on certain avian hosts is likely to be inherent, and we discuss the implications innate host preferences may have on enzootic WNV transmission.

Authors

Simpson, Jennifer E., Folsom-O'Keefe, Corrine M., Childs, James E., Simons, Leah E., Andreadis, Theodore G. and Diuk-Wasser, Maria A.

Year Published

2009

Publication

PLOS One

Locations
DOI

10.1371/journal.pone.0007861

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19924251

Human Bloodfeeding by the Recently Introduced Mosquito, Aedes japonicus japonicus, and Public Health ImplicationsMolaei, Goudarz2009

Human Bloodfeeding by the Recently Introduced Mosquito, Aedes japonicus japonicus, and Public Health Implications

Keywords

WNV

Abstract

Knowledge of the host-feeding behavior and extent of interactions with human hosts are important in evaluating the role and vector potential of invasive mosquitoes in transmission of native arboviruses. We collected blood-engorged females of the recently established exotic species Aedes japonicus japonicus from sites in New Jersey during 2000 to 2007 and identified the sources of vertebrate blood meals by sequencing portions of the cytochrome b gene of mitochondrial DNA. Over 1/3 (36%, n = 36) of the engorged mosquitoes acquired blood meals from humans. Other mammalian hosts included white-tailed deer (53%), fallow deer (5%), horse (3%), and Virginia opossum (3%). No avian, amphibian, reptilian, or mixed blood meals were identified. Our detection of a comparatively high prevalence of human bloodfeeding in Ae. j. japonicus in association with its local abundance, vector competence, and repeated detection of West Nile virus from field-collected specimens illustrates the potential for this invasive mosquito to serve as a "bridge" vector in transmission of West Nile and other mosquito-borne viruses in North America.

Authors

Molaei, Goudarz, Farajollahi, Ary, Scott, Jamesina J., Gaugler, Randy and Andreadis, Theodore G.

Year Published

2009

Publication

Journal of the American Mosquito Control Association

Locations
DOI

10.2987/09-0012.1

Additional Information:

http://www.ncbi.nlm.nih.gov/pubmed/19653507

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