| Rural Cases of Equine West Nile Virus Encephalomyelitis and the Normalized Difference Vegetation Index | Ward, Michael P. | 2005 |
KeywordsWNV AbstractData from an outbreak (August to October, 2002) of West Nile virus (WNV) encephalomyelitis in a population of horses located in northern Indiana was scanned for clusters in time and space. One significant (p = 0.04) cluster of case premises was detected, occurring between September 4 and 10 in the south-west part of the study area (85.70°N, 45.50°W). It included 10 case premises (3.67 case premises expected) within a radius of 2264 m. Image data were acquired by the Advanced Very High Resolution Radiometer (AVHRR) sensor onboard a National Oceanic and Atmospheric Administration polar-orbiting satellite. The Normalized Difference Vegetation Index (NDVI) was calculated from visible and near-infrared data of daily observations, which were composited to produce a weekly-1km2 resolution raster image product. During the epidemic, a significant (p < 0.01) decrease (0.025 per week) in estimated NDVI was observed at all case and control premise sites. The median estimated NDVI (0.659) for case premises within the cluster identified was significantly (p < 0.01) greater than the median estimated NDVI for other case (0.571) and control (0.596) premises during the same period. The difference in median estimated NDVI for case premises within this cluster, compared to cases not included in this cluster, was greatest (5.3% and 5.1%, respectively) at 1 and 5 weeks preceding occurrence of the cluster. The NDVI may be useful for identifying foci of WNV transmission. Vector-Borne Zoonotic Dis. 5, 181–188. AuthorsWard, Michael P., Ramsay, Bruce H. and Gallo, Kevin Year Published2005 PublicationVector-Borne and Zoonotic Diseases LocationsDOI10.1089/vbz.2005.5.181 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16011435 |
| West Nile Virus Detection in Kidney, Cloacal, and Nasopharyngeal Specimens | Ohajuruka, Ojimadu A. | 2005 |
KeywordsWNV AbstractWe compared kidney tissue samples and cloacal and nasopharyngeal swab samples from field-collected dead crows and blue jays for West Nile virus surveillance. Compared to tissue samples, 35% more swab samples were false negative. Swab samples were usually positive only when the corresponding tissue sample was strongly positive. AuthorsOhajuruka, Ojimadu A., Berry, Richard L., Grimes, Sheila and Farkas, Susanne Year Published2005 PublicationEmerging Infectious Diseases LocationsDOI10.3201/eid1209.050016 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16229775 |
| Culex restuans (Diptera: Culicidae) Relative Abundance and Vector Competence for West Nile Virus | Ebel, Gregory D. | 2005 |
KeywordsCulex pipiens, Culex restuans, West Nile virus, Flavivirus, transmission, WNV AbstractThe abundance and vector competence of Culex restuans Theobald and Culex pipiens L. were compared to determine the relative importance of these species as West Nile virus (WNV) vectors in the northeastern United States. Abundance was estimated from egg raft collections at 12 sites in Albany, Suffolk, and Richmond counties, New York, during July, August, and September 2002 and 2003. Cx. restuans was more abundant than Cx. pipiens in both urban and rural areas, comprising 86% of 1,623 egg rafts collected. Vector competence for WNV was estimated after feeding on an artificial bloodmeal and in vitro transmission assays. The vector competence of the two species for WNV was similar, but the dynamics of infection seems to be mosquito species dependent. These findings suggest an important role for Cx. restuans in WNV transmission cycles in New York. AuthorsEbel, Gregory D., Rochlin, Ilia, Longacker, Jennifer and Kramer, Laura D. Year Published2005 PublicationJournal of Medical Entomology LocationsDOI10.1603/0022-2585(2005)042[0838:CRDCRA]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16363169 |
| Surveillance of Above- and Below-Ground Mosquito Breeding Habitats in a Rural Midwestern Community: Baseline Data for Larvicidal Control Measures Against West Nile Virus Vectors | Kronenwetter-Koepel, T. A. | 2005 |
KeywordsMosquito control, Breeding, Environment, West Nile virus, Culex, WNV AbstractBackground Mosquitoes in the genus Culex are thought to play a major role as vectors in the transmission cycle of West Nile virus (WNV) and other arboviruses in the United States. Effective control of mosquitoes through larviciding and adulticiding is expensive for communities and should be guided by reliable surveillance data on the distribution of mosquito breeding habitats. However, few small to medium sized cities in rural areas of the midwestern United States have this type of baseline information available.
Objective During the summer of 2004, we investigated the characteristics of Culex and other mosquito-breeding habitats in a rural central Wisconsin community with a population of approximately 19,000. Such baseline information will aid in the development of rational strategies to control mosquito populations and prevent human exposure to WNV and other mosquito-transmitted viruses.
Methods Mosquito larvae were collected and identified weekly from 14 below-ground storm water catch basins and 10 above-ground standing water sites distributed throughout the community. Collection began June 4, 2004 and continued through September 24, 2004. For each collection site the primary and adjacent land use patterns were determined.
Results Over the study period, 1,244 larvae were collected from catch basins; 94% were Culex species. Breeding activity was first detected in early July. Peak breeding was observed during a period of several weeks when average daily temperatures were at the maximum observed and rainfall had declined. Organically enriched catch basins in low intensity urban sites adjacent to forests and wetlands were found to be more productive breeding habitats compared to catch basins having little organic debris located in isolated high intensity urban sites. Above-ground standing water sites produced 1,504 larvae; 66% of which were Culex species. Flood control ditches and permanent wetlands with stagnant water were most productive, while ditches with moving water were least productive habitats. Larvae were produced earlier in the season by above-ground sites than were produced by catch basins. However, larvae production was more variable in above-ground sites since half the sites became dry at some point during the study period.
Conclusion The observed differences in Culex larvae production based on the variables of habitat-type, temperature, and precipitation support the need for ongoing surveillance in communities to guide public health officials in planning for and prioritizing mosquito control efforts. AuthorsKronenwetter-Koepel, T. A., Meece, J. K., Miller, C. A. and Reed, K. D. Year Published2005 PublicationClinical Medicine & Research LocationsDOI10.3121/cmr.3.1.3 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/15962015 |
| Serologic Evidence of West Nile Virus Infection in Three Wild Raptor Populations | Stout, William E. | 2005 |
KeywordsWest Nile virus, passive maternal antibody transmission, Cooper's hawk, great horned owl, red-tailed hawk, WNV AbstractWe assayed for West Nile virus (WNV) antibodies to determine the presence and prevalence of WNV infection in three raptor populations in southeast Wisconsin during 2003–04. This study was conducted in the framework of ongoing population studies that started before WNV was introduced to the study area. For 354 samples, 88% of 42 adult Cooper's hawks (Accipiter cooperii), 2.1% of 96 nestling Cooper's hawks, 9.2% of 141 nestling red-tailed hawks (Buteo jamaicensis), and 12% of 73 nestling great horned owls (Bubo virginianus) tested positive for WNV antibodies by the constant virus–serum dilution neutralization test. Samples that tested positive for WNV antibodies were collected across a wide variety of habitat types, including urban habitats (both high and low density), roads, parking areas, recreational areas, croplands, pastures, grasslands, woodlands, and wetlands. Based on the increased prevalence and significantly higher WNV antibody titers in adults compared with nestlings, we suggest that nestlings with detectable antibody levels acquired these antibodies through passive transmission from the mother during egg production. Low levels of WNV antibodies in nestlings could serve as a surrogate marker of exposure in adult raptor populations. Based on breeding population densities and reproductive success over the past 15 yr, we found no apparent adverse effects of WNV infections on these wild raptor populations. AuthorsStout, William E., Cassini, Andrew G., Meece, Jennifer K., Papp, Joseph M., Rosenfield, Robert N. and Reed, Kurt D. Year Published2005 PublicationAvian Diseases LocationsDOI10.1637/7335-012805R1.1 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16252490 |
| FACTORS CONTRIBUTING TO PROCESS VARIANCE IN ANNUAL SURVIVAL OF FEMALE GREATER SAGE-GROUSE IN MONTANA | Moynahan, Brendan J. | 2006 |
Keywordsbreeding status vs. survival;Centrocercus urophasianus;Greater Sage-Grouse;habitat protection;known fate;Montana, USA;population dynamics;process variance;program MARK;sagebrush;survival estimation;winter weather AbstractPopulations of Greater Sage-Grouse (Centrocercus urophasianus) have declined by 69–99% from historic levels, and information on population dynamics of these birds at a landscape scale is essential to informed management. We examined the relationships between hen survival and a suite of landscape-scale habitat and environmental conditions. We radio-marked 237 female Sage-Grouse and measured 426 vegetation plots during 2001–2004 at four sites in a 3200-km2 landscape in north-central Montana, USA. We used program MARK to model monthly survival rates for 11 seasonal intervals. There was strong support for the best-approximating model (AICc weight = 0.810), which indicated that (1) hen survival varied by season within years and by year within seasons, (2) nesting hens had higher nesting-season survival than non-nesting hens, and (3) individuals at one site had lower hunting-season survival than at other sites. We observed considerable variation in hen survival. Process variation was 0.255, with an expected range of annual survival of 0.12 to 1.0. The ratio of process to total variation was 0.999, indicating that observed variation was real and not attributable to sampling variation. We observed a nearly fourfold difference in maximum and minimum annual survival, ranging from 0.962 ± 0.024 (mean ± se) for nesting hens in 2001–2002 to 0.247 ± 0.050) for non-nesters in 2003–2004. Low annual survival in 2003 resulted from the compounded effects of a West Nile virus outbreak in August and a severe winter in 2003–2004. Increased hen mortality associated with severe winter weather contrasts with prior beliefs that Sage-Grouse populations are typically unaffected by winter weather conditions and underscores the importance of protecting winter sagebrush (Artemisia spp.) habitats. AuthorsMoynahan, Brendan J., Mark S. Lindberg, and Jack Ward Thomas. Year Published2006 PublicationEcological Applications LocationsDOI10.1890/1051-0761(2006)016[1529:FCTPVI]2.0.CO;2 This article contributed by:Ecological Society of America |
| Susceptibility of greater sage-grouse to experimental infection with West Nile virus | Clark, L | 2006 |
Susceptibility of greater sage-grouse to experimental infection with West Nile virusKeywordsCentrocercus urophasianus
experimental infection
greater sage-grouse
vaccine
West Nile virus AbstractPopulations of greater sage-grouse (Centrocercus urophasianus) have declined 45-80% in North America since 1950. Although much of this decline has been attributed to habitat loss, recent field studies have indicated that West Nile virus (WNV) has had a significant negative impact on local populations of grouse. We confirm the susceptibility of greater sage-grouse to WNV infection in laboratory experimental studies. Grouse were challenged by subcutaneous injection of WNV (10(3.2) plaque-forming units [PFUs]). All grouse died within 6 days of infection. The Kaplan-Meier estimate for 50% survival was 4.5 days. Mean peak viremia for nonvaccinated birds was 10(6.4) PFUs/ml (+/- 10(0.2) PFUs/ml, standard error of the mean [SEM]). Virus was shed cloacally and orally. Four of the five vaccinated grouse died, but survival tune was increased (50% survival = 9.5 days), with 1 grouse surviving to the end-point of the experiment (14 days) kith no signs of illness. Mean peak viremia for the vaccinated birds was 10(2.3) PFUs/ml (+/- 10(0.6) PFUs/ml, SEM). Two birds cleared the virus from their blood before death or euthanasia. These data emphasize the high susceptibility of greater sage-grouse to infection with WNV. AuthorsClark, L; Hall, J; McLean, R; Dunbar, M; Klenk, K; Bowen, R; Smeraski, CA Year Published2006 PublicationJournal of Wildlife Diseases Locations |
| 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 |
