west nile virus infection and serologic response among persons previously vaccinated against yellow fever and japanese encephalitis is hypothesized that previous heterologous flaviviral exposure may modulate clinical illness among persons infected with west nile virus (wnv). little is known about the serological response in such persons. in summer 2003, a wnv outbreak occurred in colorado, the location of the centers for disease control and prevention, division of vector-borne infectious diseases (dvbid). dvbid employees, most previously vaccinated with yellow fever virus (yfv) or japanese encephalitis virus (jev) vaccine ...200516011430
surveillance for west nile virus in clinic-admitted raptors, 2005, 13.5% of clinic-admitted raptors in northern colorado tested positive for west nile virus (wnv). clinic-admitted-raptor surveillance detected wnv activity nearly 14 weeks earlier than other surveillance systems. wnv surveillance using live raptor admissions to rehabilitation clinics may offer a novel surveillance method and should be considered along with other techniques already in use.200717479898
west nile virus neuroinvasive disease incidence in the united states, the geographic range of reported human west nile virus (wnv) disease has expanded across the united states, seasonal transmission and outbreaks have persisted over several years in many areas of the country. west nile virus neuroinvasive disease (wnnd) case reports from 2002 to 2006 were reviewed to determine which areas of the country have the highest reported cumulative incidence and whether those areas have had consistently high annual incidence. during the 5-year period examined, 9632 cas ...200818237264
combining mosquito vector and human disease data for improved assessment of spatial west nile virus disease risk.assessments of spatial risk of exposure to vector-borne pathogens that combine vector and human disease data are needed for areas encompassing large tracts of public land with low population bases. we addressed this need for west nile virus (wnv) disease in the northern colorado front range by developing not only a spatial model for entomological risk of exposure to culex tarsalis wnv vectors and an epidemiological risk map for wnv disease but also a novel risk-classification index combining dat ...200818385365
persistent west nile virus transmission and the apparent displacement st. louis encephalitis virus in southeastern california, 2003-2006.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, ind ...200818533445
environmental predictors of human west nile virus infections, determine whether environmental surveillance of west nile virus-positive dead birds, mosquito pools, equines, and sentinel chickens helped predict human cases in metropolitan denver, colorado, during 2003, we analyzed human surveillance data and environmental data. birds successfully predicted the highest proportion of human cases, followed by mosquito pools, and equines.200718217573
genetic deficiency of chemokine receptor ccr5 is a strong risk factor for symptomatic west nile virus infection: a meta-analysis of 4 cohorts in the us epidemic.west nile virus (wnv) causes disease in approximately 20% of infected humans. we previously reported that homozygosity for ccr5delta32, a nonfunctional variant of chemokine receptor ccr5, is markedly increased among symptomatic wnv-seropositive patients from arizona and colorado. to confirm this, we analyzed cohorts from california and illinois. an increase in ccr5-deficient subjects was found in both (for california, odds ratio [or], 4.2 [95% confidence interval {ci}, 1.5-11.9] [p= .004]; for i ...200818179388
west nile viremic blood donors and risk factors for subsequent west nile fever.while increasing age is a known risk factor for neuroinvasive west nile virus (wnv) disease, little is known about risk factors for west nile fever (wnf). in 2003, united states blood centers identified wn (west nile) viremic donors using nucleic acid-amplification tests (nats), making it possible to prospectively determine risk factors for wnf. we report the characteristics of wn viremia among donors at colorado's largest blood center and risk factors for wnf in viremic donors.200717979539
spatio-temporal cluster analysis of county-based human west nile virus incidence in the continental united states.west nile virus (wnv) is a vector-borne illness that can severely affect human health. after introduction on the east coast in 1999, the virus quickly spread and became established across the continental united states. however, there have been significant variations in levels of human wnv incidence spatially and temporally. in order to quantify these variations, we used kulldorff's spatial scan statistic and anselin's local moran's i statistic to uncover spatial clustering of human wnv incidence ...200919594928
west nile virus detection in nonvascular feathers from avian carcasses.west nile virus (wnv) is a public health threat and has caused the death of thousands of north american birds. as such, surveillance for wnv has been ongoing, utilizing numerous biological specimens and testing methods. nonvascular (i.e., fully grown) feathers would provide a simple method of collection from either dead or live birds of all ages and molt cycles, with presumably less biosafety risk compared with other specimen types, including feather pulp. the current study evaluates wnv detecti ...200919737756
behavioral risks for west nile virus disease, northern colorado, 2003, residents in 2 adjacent cities in northern colorado (loveland and fort collins) had severe outbreaks of human west nile virus (wnv) disease. unexpectedly, age-adjusted neuroinvasive disease rates were higher in loveland (38.6 vs. 15.9 per 100,000), which had a more extensive mosquito control program and fewer mosquitoes. a survey was conducted to assess differences in personal protection and risk practices by each city's residents. during may and june 2004, a random-digit dial telephone ...200717552095
entomological studies along the colorado front range during a period of intense west nile virus 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 ...200717536366
west nile virus activity--united states, january 1-august 15, 2006.this report summarizes west nile virus (wnv) surveillance data reported to cdc through arbonet as of 3 a.m. mountain daylight time, august 15, 2006. a total of 26 states had reported 388 cases of human wnv illness to cdc. a total of 214 (56%) cases for which such data were available occurred in males; median age of patients was 49 years (range: 2-91 years). dates of illness onset ranged from january 6 to august 10; a total of 13 cases were fatal. a total of 68 presumptive west nile viremic blood ...200616915222
follow-up of 2003 human west nile virus infections, denver, colorado.tri-county health department and boulder county public health conducted a follow-up study of all nonfatal west nile virus (wnv) cases reported during 2003 in 4 metropolitan denver, colorado, counties. self-reported patient information was obtained approximately 6 months after onset. a total of 656 (81.2%) eligible wnv patients are included in this study.200616836833
role of corvids in epidemiology of west nile virus in southern california.the invasion of different southern california landscapes by west nile virus (wnv) and its subsequent amplification to epidemic levels during 2004 enabled us to study the impact of differing corvid populations in three biomes: the hot colorado desert with few corvids (coachella valley), the southern san joaquin valley (kern county) with large western scrub-jay but small american crow populations, and the cool maritime coast (los angeles) with a large clustered american crow population. similar su ...200616619622
west nile virus disease: a descriptive study of 228 patients hospitalized in a 4-county region of colorado in 2003.risk factors for complications of west nile virus disease and prognosis in hospitalized patients are incompletely understood.200616586381
west nile virus infection among pregnant women in a northern colorado community, 2003 to 2004.since west nile virus (wnv) was first detected in new york in 1999, it has spread across north america and become a major public health concern. in 2002, the first documented case of intrauterine wnv infection was reported, involving an infant with severe brain abnormalities. to determine the frequencies of wnv infections during pregnancy and of intrauterine wnv infections, we measured wnv-specific antibodies in cord blood from infant deliveries after a community-wide epidemic of wnv disease.200616510662
evaluation of factors associated with positive igm capture elisa results in equids with clinical signs compatible with west nile virus infection: 1,017 cases (2003).to describe the prevalence of west nile virus (wnv) infection and evaluate factors associated with positive igm capture elisa results in equids with clinical signs compatible with wnv infection.200616448369
west nile virus infection. highlights from the fifth national conference on west nile virus in the united states, jointly sponsored by the centers for disease control and prevention (cdc) and the american society for microbiology (asm), february 2-5, 2004, denver, co. 200416400263
west nile virus disease and other arboviral diseases --- united states, 2010.arthropod-borne viruses (arboviruses) are transmitted to humans primarily through the bites of infected mosquitoes and ticks. since west nile virus (wnv) was first detected in the western hemisphere in 1999, it has become the leading cause of neuroinvasive arboviral disease in the united states. however, several other arboviruses continue to cause sporadic cases and seasonal outbreaks of neuroinvasive disease (i.e., meningitis, encephalitis, or acute flaccid paralysis). this report summarizes su ...201121814163
serologic evidence of exposure of wild mammals to flaviviruses in the central and eastern united states.serosurveys were conducted to obtain flavivirus and west nile virus (wnv) seroprevalence data from mammals. sera from 513 small- and medium-sized mammals collected during late summer and fall 2003 from colorado, louisiana, new york, ohio, and pennsylvania were screened for flavivirus-specific antibodies. sera samples containing antibody to flaviviruses were screened for wnv-specific antibodies by epitope-blocking enzyme-linked immunosorbent assays and confirmed with plaque reduction neutralizati ...200515891139
the 2003 west nile virus united states epidemic: the america's blood centers experience.a detailed assessment of west nile virus (wnv) yield is needed to evaluate the effectiveness of the wnv nucleic acid amplification technology (nat) screening implemented in 2003.200515819665
west nile virus activity--united states, october 13-19, 2004.during october 13-19, a total of 200 cases of human west nile virus (wnv) illness were reported from 20 states (arizona, arkansas, california, colorado, illinois, indiana, iowa, kansas, maryland, michigan, mississippi, missouri, nevada, new mexico, north carolina, oklahoma, pennsylvania, south dakota, wisconsin, and wyoming).200415499683
perceptual influences on self-protective behavior for west nile virus, a survey in colorado, usa.the endemic state of west nile virus (wnv) in north america underscores the need to examine mechanisms influencing human self-protective behavior. based on previous findings and theory, this study is designed to achieve two specific aims. first, the study will examine self-protective behavior for wnv through a hybridized treatment of the health belief model that includes cognitive, affective, ecological, and proximity risk perception measures. second, within the resulting hybridized model explor ...201526082139
west nile virus activity--united states, september 8-14, 2004.during september 8-14, a total of 195 cases of human west nile virus (wnv) illness were reported from 26 states (alabama, arizona, arkansas, california, colorado, florida, georgia, idaho, illinois, iowa, kansas, maryland, minnesota, missouri, nebraska, nevada, new mexico, new york, north dakota, oklahoma, oregon, pennsylvania, south dakota, tennessee, texas, and wisconsin).200415371969
west nile virus activity--united states, august 18-24, 2004.during august 18-24, a total of 154 cases of human west nile virus (wnv) illness were reported from 18 states (alabama, arizona, california, colorado, connecticut, florida, georgia, illinois, kentucky, minnesota, mississippi, missouri, nevada, new mexico, north carolina, south dakota, tennessee, and wisconsin).200415329654
outcome of equids with clinical signs of west nile virus infection and factors associated with determine outcome of equids in the western united states with clinical signs of west nile virus (wnv) infection and identify factors associated with risk of death in infected equids.200415323385
west nile virus activity--united states, august 11-17, 2004.during august 11-17, a total of 194 cases of human west nile virus (wnv) illness were reported from 17 states (alabama, arizona, california, colorado, florida, illinois, louisiana, maryland, minnesota, mississippi, missouri, new mexico, ohio, south dakota, texas, utah, and virginia).200415318160
naturally acquired west nile virus encephalomyelitis in transplant recipients: clinical, laboratory, diagnostic, and neuropathological the 2003 west nile virus (wnv) epidemic, colorado reported more wnv cases than any other state, including an unprecedented number in organ transplant recipients.200415313837
west nile virus activity--united states, july 28-august 3, 2004.during july 28-august 3, a total of 141 cases of human west nile virus (wnv) illness were reported from 11 states (alabama, arizona, california, colorado, florida, illinois, nevada, new york, north dakota, south dakota, and texas). during 2004, a total of 20 states have reported a total of 406 cases of human wnv illness to cdc through arbonet. of these, 247 (61%) were reported from arizona. a total of 226 (57%) of the 406 cases occurred in males; the median age of patients was 51 years (range: 1 ...200415295314
west nile virus activity--united states, july 21-27, 2004.during july 21-27, a total of 83 cases of human west nile virus (wnv) illness were reported from 13 states (alabama, arizona, arkansas, california, colorado, florida, illinois, iowa, missouri, new mexico, ohio, pennsylvania, and south dakota).200415282450
study: west nile virus cost equine industries in colorado, nebraska millions in 2002. 200312830851
mosquito species richness, composition, and abundance along habitat-climate-elevation gradients in the northern colorado front range.we exploited elevation gradients (1,500-2,400 m) ranging from plains to montane areas along the poudre river and big thompson river in the northern colorado front range to determine how mosquito species richness, composition, and abundance change along natural habitat-climate-elevation gradients. mosquito collections in 26 sites in 2006 by using co2-baited cdc light traps yielded a total of 7,136 identifiable mosquitoes of 27 species. commonly collected species included aedes vexans (meigen) (n ...200818714885
predictive spatial models for risk of west nile virus exposure in eastern and western the absence of a vaccine for use in humans against west nile virus (wnv), mosquito control and personal protection against mosquito bites are the only measures available to prevent disease. improved spatial targeting is desirable for costly mosquito and wnv surveillance and control schemes. we used a multivariate regression modeling approach to develop spatial models predicting high risk of exposure to wnv in western and eastern colorado based on associations between geographic information sy ...200818840749
seasonal blood-feeding behavior of culex tarsalis (diptera: culicidae) in weld county, colorado, 2007.studies on culex tarsalis coquillett in colorado have shown marked seasonal variation in the proportion of blood meals from birds and mammals. however, limitations in the specificity of antibodies used in the precipitin test and lack of vertebrate host availability data warrant revisiting cx. tarsalis blood feeding behavior in the context of west nile virus (wnv) transmission. we characterized the host preference of cx. tarsalis during peak wnv transmission season in eastern colorado and estimat ...200919351092
relationship between distance from major larval habitats and abundance of adult mosquitoes in semiarid plains landscapes in colorado.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 ...200919960672
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.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 >1600 m compared with pl ...200919960707
spatial risk assessments based on vector-borne disease epidemiologic data: importance of scale for west nile virus disease in colorado.we used epidemiologic data for human west nile virus (wnv) disease in colorado from 2003 and 2007 to determine 1) the degree to which estimates of vector-borne disease occurrence is influenced by spatial scale of data aggregation (county versus census tract), and 2) the extent of concordance between spatial risk patterns based on case counts versus incidence. statistical analyses showed that county, compared with census tract, accounted for approximately 50% of the overall variance in wnv diseas ...201020439980
west nile virus activity - united states, 2009.west nile virus (wnv) was first detected in the western hemisphere in 1999 in new york city and has since caused seasonal epidemics of febrile illness and neurologic disease across the united states, where it is now the leading cause of arboviral encephalitis. this report updates a previous report and summarizes wnv activity in the united states reported to cdc in 2009. a total of 38 states and the district of columbia (dc) reported 720 cases of wnv disease. of these, 33 states and dc reported 3 ...201020592686
hydrologic conditions describe west nile virus risk in colorado.we examine the relationship between hydrologic variability and the incidence of human disease associated with west nile virus (wnv; family flaviviridae, genus flavivirus) infection (hereafter termed "human wn cases") in colorado from 2002 to 2007. we find that local hydrologic conditions, as simulated by the mosaic hydrology model, are associated with differences in human wn cases. in colorado's eastern plains, wetter spring conditions and drier summer conditions predict human wn cases. in color ...201020616987
mosquitoes and west nile virus along a river corridor from prairie to montane habitats in eastern colorado.we conducted studies on mosquitoes and west nile virus (wnv) along a riparian corridor following the south platte river and big thompson river in northeastern colorado and extending from an elevation of 1,215 m in the prairie landscape of the eastern colorado plains to 1,840 m in low montane areas at the eastern edge of the rocky mountains in the central part of the state. mosquito collection during june-september 2007 in 20 sites along this riparian corridor yielded a total of 199,833 identifia ...200920836831
west nile virus activity united states, july 7-13, 2004.during the week of july 7-13, a total of 30 human west nile virus illness cases were reported from four states (arizona, california, colorado, and iowa). during 2004, a total of 10 states have reported a total of 108 cases of human west nile virus (wnv) illness to cdc through arbonet. of these, 66 (61%) were reported from arizona. sixty-one (58%) of the 108 cases occurred in males; median age of patients was 52 years (range: 1-84 years); dates of illness onset ranged from april 23 to july 5; and ...200415254454
use of hospital discharge data to evaluate notifiable disease reporting to colorado's electronic disease reporting system.notifiable disease surveillance systems are critical for communicable disease control, and accurate and timely reporting of hospitalized patients who represent the most severe cases is important. a local health department in metropolitan denver used inpatient hospital discharge (ihd) data to evaluate the sensitivity, timeliness, and data quality of reporting eight notifiable diseases to the colorado electronic disease reporting system (cedrs).201121337935
insect-specific flaviviruses from culex mosquitoes in colorado, with evidence of vertical transmission.mosquitoes were collected in colorado during 2006 and 2007 to examine spatial and seasonal patterns of risk for exposure to culex vectors and west nile virus. we used universal flavivirus primers to test pools of culex mosquitoes for viral rna. this led to the detection and subsequent isolation of two insect-specific flaviviruses: culex flavivirus (cxfv), which was first described from japan, and a novel insect flavivirus, designated calbertado virus (clbov), which has also been detected in cali ...201121734144
predicting human west nile virus infections with mosquito surveillance data.west nile virus (wnv) has become established across the americas with recent heightened activity causing significant human illness. surveillance methods to predict the risk of human infection are urgently needed to initiate timely preventative measures and justify the expense of implementing costly or unpopular control measures, such as aerial spraying or curfews. we quantified the links between mosquito surveillance data and the spatiotemporal patterns of 3,827 human wnv cases reported over 5 y ...201323825164
initial and long-term costs of patients hospitalized with west nile virus disease.there are no published data on the economic burden for specific west nile virus (wnv) clinical syndromes (i.e., fever, meningitis, encephalitis, and acute flaccid paralysis [afp]). we estimated initial hospital and lost-productivity costs from 80 patients hospitalized with wnv disease in colorado during 2003; 38 of these patients were followed for 5 years to determine long-term medical and lost-productivity costs. initial costs were highest for patients with afp (median $25,117; range $5,385-$28 ...201424515937
characterization of culex pipiens complex (diptera: culicidae) populations in colorado, usa using microsatellites.mosquitoes such as those in the culex pipiens complex are important vectors of disease. this study was conducted to genetically characterize cx. pipiens complex populations in the state of colorado, usa, and to determine the number of genetic clusters represented by the data. thirteen populations located among four major river basins were sampled (nā€Š=ā€Š597 individuals) using a panel of 14 microsatellites. the lowest-elevation sites had the highest expected heterozygosity (h(e)) values (range 0.54 ...201223094068
temporal and spatial variability of entomological risk indices for west nile virus infection in northern colorado: 2006-2013.west nile virus (wnv) is enzootic in northern colorado. annual surveillance activities in fort collins, co, include collecting female culex mosquitoes and testing them for the presence of wnv rna in order to calculate 1) culex female abundance, 2) wnv infection rate, and 3) the vector index (vi). these entomological risk indices inform public policy regarding the need for emergency adulticiding. currently, these are calculated on a city-wide basis. in this study, we present descriptive data from ...201626718715
modeling culex tarsalis abundance on the northern colorado front range using a landscape-level approach.remote sensing and geographic information system (gis) data can be used to identify larval mosquito habitats and predict species distribution and abundance across a landscape. an understanding of the landscape features that impact abundance and dispersal can then be applied operationally in mosquito control efforts to reduce the transmission of mosquito-borne pathogens. in an effort to better understand the effects of landscape heterogeneity on the abundance of the west nile virus (wnv) vector c ...201424772672
examination of the geographical variation in human west nile virus: a spatial filtering approach.this paper examines the importance of environmental factors (mosquito pools and home foreclosures) in human west nile virus (wnv) transmission in california and colorado. the role of environmental factors is investigated by applying an instrumental variable technique to a spatial filtering random-effects negative binomial model to correct for both spatial autocorrelation and endogeneity. the results suggest that mosquito pools and home foreclosures are significant in explaining the prevalence of ...201424512765
fatal west nile virus infection after probable transfusion-associated transmission--colorado, 2012. 201323925171
bird community composition linked to human west nile virus cases along the colorado front the present study, we examined whether bird community composition can predict the annual number of human west nile virus (wnv) cases on a per county basis in the colorado front range, a region that experienced high numbers of human cases during the early part of the north american epidemic. we analyzed data sets pertaining to birds and human wnv cases from multiple existing databases between the years 2002 and 2008. based on previous studies that used amplification fractions to compare the re ...201021125307
irrigated agriculture is an important risk factor for west nile virus disease in the hyperendemic larimer-boulder-weld area of north central colorado.this study focused on two west nile virus (wnv) disease outbreak years, 2003 and 2007, and included a three-county area (larimer, boulder, and weld) in north central colorado that is hyperendemic for wnv disease. we used epidemiological data for reported wnv disease cases at the census tract scale to: (1) elucidate whether wnv disease incidence differs between census tracts classified as having high versus lower human population density (based on a threshold value of 580 persons/km2) and (2) det ...201020939393
the effect of spatial and temporal subsetting on culex tarsalis abundance models--a design for sensible reduction of vector surveillance.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 describin ...201121805843
delayed mortality in a cohort of persons hospitalized with west nile virus disease in colorado in 2003.abstract most mortality associated with west nile virus (wnv) disease occurs during the acute or early convalescent phases of illness. however, some reports suggest mortality may be elevated for months or longer after acute illness. the objective of this study was to assess the survival of a cohort of patients hospitalized with wnv disease in colorado in 2003 up to 4 years after illness onset. we calculated age-adjusted standardized mortality ratios (smrs) to evaluate excess mortality, evaluat ...201122022816
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