| WEST NILE VIRUS SURVEILLANCE IN MOSQUITOES IN NEW YORK STATE, 2000–2004 | LUKACIK, GARY | 2006 |
KeywordsWest Nile virus, Culex, virus surveillance, gravid traps, WNV AbstractA West Nile virus (WNV) surveillance system was created and implemented in New York State (NYS) in 2000 and described previously (White et al. 2001). We examine and evaluate the results of mosquito and virus surveillance for 2000 through 2004 exclusive of New York City. Forty-nine counties submitted 1,095,426 mosquitoes in 35,280 pools for WNV assay. Specimens of 47 species were tested, with Culex species accounting for 47.6% of all pools tested. WNV was detected in 814 pools from 10 species, with combined Culex pipiens/Culex restuans pools accounting for 90.8% of all detections. Pools submitted from gravid traps were 5.7 times more likely to be positive than submissions from carbon dioxide-baited light traps. Most human WNV cases resided in counties that conducted mosquito surveillance. Local health departments' use of mosquito surveillance information often led to an enhanced disease prevention response. In NYS, Cx. pipiens/Cx. restuans group are the most likely vectors of WNV. Future efforts to improve system efficacy are discussed. AuthorsWHITE, DENNIS J., Kramer, Laura D., LUKACIK, GARY, ANAND, MADHU, SHUSAS, EMILY J., HOWARD, JOHN J., OLIVER, JOANNE, CHEN, HAIYAN, BACKENSON, P. BRYON, KAUFFMAN, ELIZABETH B. and BERNARD, KRISTEN A. Year Published2006 PublicationJournal of the American Mosquito Control Association LocationsDOI10.2987/8756-971X(2006)22[264:WNVSIM]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/17019772 |
| Emergence of West Nile Virus in Mosquito (Diptera: Culicidae) Communities of the New Mexico Rio Grande Valley | DiMenna, Mark A. | 2006 |
KeywordsWest Nile virus, New Mexico Rio Grande, mosquitoes, emergence, WNV AbstractThe first appearances of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in New Mexico were reported in late summer to early fall 2002. Several dead birds tested positive for WNV, and 78 equine cases were confirmed. All mosquito pools tested (n = 268) were negative. A statewide surveillance program was launched in May 2003 to study the emergence and spread of this new arbovirus in mosquitoes from the Rio Grande valley. Mosquitoes were trapped at 32 sites along a 750-km stretch of the Rio Grande valley. Sites were trapped for one night either weekly or biweekly, by using CO2-baited CDC light traps and gravid traps. Pools of captured mosquitoes were tested for WNV by reverse transcription-polymerase chain reaction. By mid-July 2003, WNV levels in the mosquito population had reached levels that were detectable by the surveillance program. Positive pools of mosquitoes were found in the Rio Grande valley from mid-July through late September. In total, 75 positive pools were found, from sites throughout the study area. The predominant species infected with WNV in this region were Culex tarsalis (Coquillett) in rural areas, and Culex salinarius (Coquillett) and Culex pipiens quinquefasciatus (Say) in urban areas. There were 202 human cases and 438 equine cases of WNV in New Mexico in 2003, which corresponded well in time with the positive mosquitoes. Our results seemed to be consistent with introduction of WNV in late summer 2002, followed by a period of transmission and amplification cycles between local avian hosts and mosquito vectors. AuthorsParmenter, Robert R., DiMenna, Mark A., Bueno, Rudy, Norris, Douglas E., Sheyka, Jeff M., Molina, Josephine L., LaBeau, Elisa M., Hatton, Elizabeth S. and Glass, Gregory E. Year Published2006 PublicationJournal of Medical Entomology Locations- Alamosa, CO (37.4694, -105.87)
- Arroyo Hondo, NM (36.5361, -105.67)
- Pilar, NM (36.2691, -105.782)
- Velarde, NM (36.1673, -105.968)
- Espanola, NM (35.991, -106.082)
- Los Alamos, NM (35.8881, -106.307)
- Santa Fe, NM (35.687, -105.938)
- Bernalillo, NM (35.0178, -106.629)
- Albuquerque, NM (35.1107, -106.61)
- Los Lunas, NM (34.8062, -106.733)
- Belen, NM (34.6628, -106.776)
- San Acacia, NM (34.2553, -106.899)
- San Acacia, NM (34.2553, -106.899)
- Socorro, NM (34.0584, -106.891)
- Bosque del Apache Wilderness (Chupadera Unit), Socorro, NM (33.8351, -106.852)
- Truth or Consequences, NM (33.1284, -107.253)
- Hatch, NM (32.6654, -107.153)
- Radium Springs, NM (32.4928, -106.911)
- Las Cruces, NM (32.3199, -106.764)
- El Paso, TX (31.7587, -106.487)
DOI10.1603/0022-2585(2006)43[594:EOWNVI]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16739421 |
| Effects of Temperature on the Transmission of West Nile Virus by Culex tarsalis (Diptera: Culicidae) | Reisen, William K. | 2006 |
KeywordsCulex tarsalis, West Nile virus, transmission, temperature, degree-days, WNV AbstractCulex tarsalis Coquillett females were infected with the NY99 strain of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) and then incubated under constant temperatures of 10–30°C. At selected time intervals, transmission was attempted using an in vitro capillary tube assay. The median time from imbibing an infectious bloodmeal until infected females transmitted WNV (median extrinsic incubation period, EIP50) was estimated by probit analysis. By regressing the EIP rate (inverse of EIP50) as a function of temperature from 14 to 30°C, the EIP was estimated to require 109 degree-days (DD) and the point of zero virus development (x-intercept) was estimated to be 14.3°C. The resulting degree-day model showed that the NY99 WNV strain responded to temperature differently than a lineage II strain of WNV from South Africa and approximated our previous estimates for St. Louis encephalitis virus (family Flaviviridae, genus Flavivirus, SLEV). The invading NY99 WNV strain therefore required warm temperatures for efficient transmission. The time for completion of the EIP was estimated monthly from temperatures recorded at Coachella Valley, Los Angeles, and Kern County, California, during the 2004 epidemic year and related to the duration of the Cx. tarsalis gonotrophic cycle and measures of WNV activity. Enzootic WNV activity commenced after temperatures increased, the duration of the EIP decreased, and virus potentially was transmitted in two or less gonotrophic cycles. Temperatures in the United States during the epidemic summers of 2002–2004 indicated that WNV dispersal and resulting epicenters were linked closely to above-average summer temperatures. AuthorsReisen, William K., Fang, Ying and Martinez, Vincent M. Year Published2006 PublicationJournal of Medical Entomology LocationsDOI10.1603/0022-2585(2006)043[0309:EOTOTT]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16619616 |
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Efficacy of Resmethrin Aerosols Applied from the Road for Suppressing
Culex
Vectors of West Nile Virus
| Reddy, Michael R. | 2006 |
KeywordsWNV AbstractWe 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. AuthorsReddy, Michael R., Spielman, Andrew, Lepore, Timothy J., Henley, David, Kiszewski, Anthony E. and Reiter, Paul Year Published2006 PublicationVector-Borne and Zoonotic Diseases LocationsDOI10.1089/vbz.2006.6.117 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16796509 |
| Field and Laboratory Evaluation of Diagnostic Assays for Detecting West Nile Virus in Oropharyngeal Swabs from California Wild Birds | Padgett, Kerry A. | 2006 |
KeywordsWNV AbstractThree diagnostic assays for detecting West Nile virus (WNV) in avian oral swabs were evaluated in California in 2004 and 2005: two commercial antigen-capture assays, VecTest and Rapid Analyte Measurement Platform (RAMP), and reverse transcriptase–polymerase chain reaction (RT-PCR) of oral swabs in a specialized viral transport medium (VTM). Results from this study demonstrated that VTM was excellent for transportation and maintenance of WNV in avian oral swab samples and allowed for detection by RT-PCR and subsequent confirmation by virus isolation. Oral swabs and kidney tissue in VTM tested by RT-PCR were found to have similar accuracy in detecting WNV in corvids. The two antigen-capture assays, VecTest and RAMP, provided few false positives for corvids, with over 95% specificity. When performed by multiple local agencies throughout the state, VecTest and RAMP were similarly sensitive for oral swabs of American Crows (Corvus brachyrhynchos) (70% and 64%, respectively). Data from known WNV positive corvid oral swabs in VTM tested by antigen-capture assays at a diagnostic laboratory suggested that RAMP was more sensitive than VecTest. Due to high probability of false negatives, neither test is recommended for use on non-corvids. While WNV antigen-capture assays were effective screening tools for corvids, they were markedly less sensitive for Western Scrub Jays (Aphelocoma californica). AuthorsWoods, Leslie, Husted, Stan, Kramer, Vicki, Padgett, Kerry A., Cahoon-Young, Barbara, Carney, Ryan and Read, Deryck Year Published2006 PublicationVector-Borne and Zoonotic Diseases LocationsDOI10.1089/vbz.2006.6.183 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16796516 |
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VECTOR COMPETENCE OF CULISETA INCIDENS AND CULEX THRIAMBUS FOR WEST NILE VIRUS
1
| Reisen, William K. | 2006 |
KeywordsCuliseta incidens (Thomson), Culex thriambus Dyar, West Nile virus, California, vector competence, WNV AbstractThe vector competence of Culiseta incidens (Thomson) and Culex thriambus Dyar for West Nile virus (WNV) were compared to Cx. quinquefasciatus Say or Cx. tarsalis Coquillett and Cx. stigmatasoma Dyar collected concurrently in California. Culiseta incidens were less susceptible to oral infection than Cx. quinquefasciatus, but transmitted virus at a significantly higher rate, thereby yielding comparable population transmission rates. Culex thriambus was equally susceptible to oral infection and transmitted virus at rates comparable to Cx. tarsalis or Cx. stigmatosoma. A mammalian host selection pattern most likely precluded detection of natural infection in Cs. incidens, a fairly abundant peridomestic species. In contrast, an avian host selection pattern and efficient vector competence resulted in repeated detection of WNV in Cx. thriambus; however, limited abundance and restrictive riparian larval habitat requirements would seem to limit the involvement of Cx. thriambus in WNV epidemiology. AuthorsReisen, William K., Fang, Ying and Martinez, Vincent M. Year Published2006 PublicationJournal of the American Mosquito Control Association LocationsDOI10.2987/8756-971X(2006)22[662:VCOCIA]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/17304934 |
| A COMPARISON OF TWO WEST NILE VIRUS DETECTION ASSAYS (TAQMAN REVERSE TRANSCRIPTASE POLYMERASE CHAIN REACTION AND VECTEST ANTIGEN ASSAY) DURING THREE CONSECUTIVE OUTBREAKS IN NORTHERN ILLINOIS | LAMPMAN, RICHARD L. | 2006 |
KeywordsCulex, VecTest™, TaqMan™ reverse transcriptase polymerase chain reaction, West Nile virus, infection rate, Cook County, Illinois, Diptera, Culicidae, WNV AbstractMosquitoes identified as female Culex (Culex) species, primarily mixtures or uniform batches of Culex pipiens and Culex restuans, were collected daily from gravid traps by 2 mosquito abatement districts (MADs) in Cook County, Illinois. From 2002 through 2004, batches (pools) of mosquitoes were tested by the MADs for West Nile virus (WNV) by using VecTest™ WNV antigen assays and the same samples were retested, usually within 1–2 wk, for WNV RNA by the TaqMan™ reverse transcriptase polymerase chain reaction (RT-PCR). There were 952 TaqMan-positive pools out of 3,953 pools over the 3 years, and about one half of that number were VecTest-positive. The difference between the 2 detection assays varied between and within years. The VecTest assays detected about 57% and 69% of the TaqMan RT-PCR–positive pools from Des Plaines Valley MAD and Northwest MAD in 2002, but only about 40% and 46% in 2003, and 36% and 55% in 2004, respectively. Based on a subset of the 2004 data, a linear relationship was found between VecTest detection of WNV and TaqMan cycle threshold between 18 and 28 cycles. A temporal decrease in the difference between the 2 assays was observed in 2003 and 2004, which we conjecture is due, at least partially, to a seasonal decline in the proportion of recently infected mosquitoes. This trend was not observed in 2002 because infection rates indicated a high likelihood of more than 1 infected mosquito per pool at the peak of transmission. Unlike a previous study, the 95% confidence intervals of infection rates based on the 2 detection methods did not always overlap. The highest infection rates occurred in 2002 when mean monthly temperatures were above average. AuthorsNovak, Robert J., LAMPMAN, RICHARD L., KRASAVIN, NINA M. and SZYSKA, MICHAEL Year Published2006 PublicationJournal of the American Mosquito Control Association LocationsDOI10.2987/8756-971X(2006)22[76:ACOTWN]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16646326 |
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Spatio-temporal Analyses of West Nile Virus Transmission in
Culex
Mosquitoes in Northern Illinois, USA, 2004
| Gu, Weidong | 2006 |
KeywordsWNV AbstractAfter a severe outbreak of West Nile virus (WNV) in Cook County, Illinois, in 2002, detections of WNV in mosquitoes were frequent across the state in the following years despite small numbers of human cases. We conducted a spatio-temporal analysis of Culex (subgenus Culex) mosquitoes collected in 2004 in three mosquito abatement districts (MAD) in Cook County by calculating monthly estimates of mosquito density, prevalence of infected mosquitoes, and exposure intensity, which in turn is a product of mosquito density and infection rates. Mosquito infections were detected early at three sites in late May and were widely detected throughout the three MADs in the summer with infection rates as high as 13 per 1000 in August. Exposure intensities were higher at sites adjacent to the Des Plaines River, especially in August and September. The aggregated pattern of WNV transmission along the river might be related to the existence of substantial forest preserves and wetlands that might produce ecological conditions favorable for mosquito proliferation and interactions between mosquitoes and birds. AuthorsGu, Weidong, Lampman, Richard, Krasavin, Nina, Berry, Robert and Novak, Robert Year Published2006 PublicationVector-Borne and Zoonotic Diseases LocationsDOI10.1089/vbz.2006.6.91 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16584331 |
| WILD BIRD MORTALITY AND WEST NILE VIRUS SURVEILLANCE: BIASES ASSOCIATED WITH DETECTION, REPORTING, AND CARCASS PERSISTENCE | Ward, Marsha R. | 2006 |
KeywordsAmerican crow, carcass, house sparrow, persistence, scavenging, surveillance, West Nile virus, WNV AbstractSurveillance targeting dead wild birds, in particular American crows (Corvus brachyrhynchos), plays a critical role in West Nile virus (WNV) surveillance in the United States. Using crow decoy surrogates, detection and reporting of crow carcasses within urban and rural environments of DeKalb County, Georgia were assessed for potential biases that might occur in the county's WNV surveillance program. In each of two replicated trials, during July and September 2003, 400 decoys were labeled with reporting instructions and distributed along randomly chosen routes throughout designated urban and rural areas within DeKalb County. Information-theoretic methods were used to compare alternative models incorporating the effects of area and trial on probabilities of detection and reporting. The model with the best empirical support included the effects of area on both detection and reporting of decoys. The proportion of decoys detected in the urban area (0.605, SE=0.024) was approximately twice that of the rural area (0.293, SE=0.023), and the proportion of decoys reported in the urban area (0.273, SE=0.023) was approximately three times that of the rural area (0.103, SE=0.028). These results suggest that human density and associated factors can substantially influence dead crow detection and reporting and, thus, the perceived distribution of WNV. In a second and separate study, the persistence and fate of American crow and house sparrow (Passer domesticus) carcasses were assessed in urban and rural environments in Athens-Clarke, Madison, and Oconee counties, Georgia. Two replicated trials using 96 carcasses of each species were conducted during July and September 2004. For a portion of the carcasses, motion sensitive cameras were used to monitor scavenging species visits. Most carcasses (82%) disappeared or were decayed by the end of the 6-day study. Carcass persistence averaged 1.6 days in rural areas and 2.1 days in urban areas. We analyzed carcass persistence rates using a known-fate model framework in program MARK. Model selection based on Akaike's Information Criteria (AIC) indicated that the best model explaining carcass persistence rates included species and number of days of exposure; however, the model including area and number of days of exposure received approximately equal support. Model-averaged carcass persistence rates were higher for urban areas and for crow carcasses. Six mammalian and one avian species were documented scavenging upon carcasses. Dead wild birds could represent potential sources of oral WNV exposure to these scavenging species. Species composition of the scavenger assemblage was similar in urban and rural areas but “scavenging pressure” was greater in rural areas. AuthorsWard, Marsha R., Stallknecht, David E., Willis, Juanette, Conroy, Michael J. and Davidson, William R. Year Published2006 PublicationJournal of Wildlife Diseases LocationsDOI10.7589/0090-3558-42.1.92 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16699152 |
| STORMWATER PONDS, CONSTRUCTED WETLANDS, AND OTHER BEST MANAGEMENT PRACTICES AS POTENTIAL BREEDING SITES FOR WEST NILE VIRUS VECTORS IN DELAWARE DURING 2004 | GINGRICH, JACK B. | 2006 |
KeywordsStormwater ponds, breeding sites, mosquito, West Nile virus, WNV AbstractWe performed longitudinal surveys of mosquito larval abundance (mean mosquito larvae per dip) in 87 stormwater ponds and constructed wetlands in Delaware from June to September 2004. We analyzed selected water quality factors, water depth, types of vegetation, degree of shade, and level of insect predation in relation to mosquito abundance. The 2004 season was atypical, with most ponds remaining wet for the entire summer. In terms of West Nile virus (WNV) vectors, wetlands predominantly produced Aedes vexans, Culex pipiens pipiens, and Culex restuans. Retention ponds generally produced the same species as wetlands, except that Cx. p. pipiens was more abundant than Cx. restuans in retention ponds. Aedes vexans and Culex salinarius were the most abundant species in Conservation Restoration Enhancement Program ponds. Sand filters uniquely produced high numbers of Cx. restuans, Cx. p. pipiens, and Aedes japonicus japonicus, a newly invasive vector species. Sites that alternately dried and flooded, mostly detention ponds, forebays of retention ponds, and some wetlands often produced Ae. vexans, an occasional WNV bridge vector species. Overall, seasonal distribution of vectors was bimodal, with peaks occurring during early and late summer. Ponds with shallow sides and heavy shade generally produced an abundance of mosquitoes, unless insect predators were abundant. Bright, sunny ponds with steep sides and little vegetation generally produced the fewest mosquitoes. The associations among mosquito species and selected vegetation types are discussed. AuthorsGINGRICH, JACK B., ANDERSON, ROBERT D., WILLIAMS, GREGORY M., O'CONNOR, LINDA and HARKINS, KEVIN Year Published2006 PublicationJournal of the American Mosquito Control Association LocationsDOI10.2987/8756-971X(2006)22[282:SPCWAO]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/17019774 |
