| Landscape-Level Spatial Patterns of West Nile Virus Risk in the Northern Great Plains | Chuang, T.-W. | 2012 |
KeywordsWNV AbstractUnderstanding the landscape-level determinants of West Nile virus (WNV) can aid in mapping high-risk areas and enhance disease control and prevention efforts. This study analyzed the spatial patterns of human WNV cases in three areas in South Dakota during 2003–2007 and investigated the influences of land cover, hydrology, soils, irrigation, and elevation by using case–control models. Land cover, hydrology, soils, and elevation all influenced WNV risk, although the main drivers were different in each study area. Risk for WNV was generally higher in areas with rural land cover than in developed areas, and higher close to wetlands or soils with a high ponding frequency. In western South Dakota, WNV risk also decreased with increasing elevation and was higher in forested areas. Our results showed that the spatial patterns of human WNV risk were associated with landscape-level features that likely reflect variability in mosquito ecology, avian host communities, and human activity. AuthorsChuang, T.-W., Hockett, C. W., Kightlinger, L. and Wimberly, M. C. Year Published2012 PublicationAmerican Journal of Tropical Medicine and Hygiene LocationsDOI10.4269/ajtmh.2012.11-0515 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/22492161 |
| Temporal and Spatial Patterns of West Nile Virus Transmission in Saginaw County, Michigan, 2003-2006 | Chuang, Ting-Wu | 2011 |
KeywordsWest Nile virus, Aedes vexans, Culex pipiens, Culex restuans, sentinel pheasants, WNV AbstractThe dynamics of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) infection in mosquitoes, sentinel pheasants, and wild dead birds were evaluated during 2003–2006 in Saginaw Co., MI. Mosquitoes were collected by New Jersey Light Traps at 22 sites during May–September, pooled by species and sample location, and tested for presence of WNV RNA by using a real-time reverse transcription-polymerase chain reaction assay. Oral swabs from wild dead birds submitted by the public were tested by Vec-Test assay. Sentinel pheasants were bled weekly, and serum was tested for antibodies with an inhibition enzyme immunoassay. In total, 37,225 mosquitoes [Aedes vexans (Meigen), Culex pipiens L., and Culex restuans Theobald] were tested in 5,429 pools, of which 59 (1.1%) were positive. Ae. vexans was most abundant but had a comparatively low infection rate (0.06–2.11) compared with Cx. pipiens (1.75–4.59) and Cx. restuans (1.22–15.67). Mosquito abundances were temporally related to variations in 2-wk average weather variables. Infected dead crows appeared earlier each transmission season than blue jays, but infection prevalence for both peaked approximately mid-August. Space-time clusters were found in different locations each year. Sentinel pheasant seroprevalence was 19.3% (16/83), 12.7% (10/79), and 7.7% (5/65) during 2003–2005, respectively. We demonstrated temporal patterns of WNV activity in corvid birds and Culex spp. mosquitoes during the study period, suggesting virus transmission within an enzootic cycle. Despite the absence of human case reports nearby, this surveillance system demonstrated WNV transmission and possible human risk. Maintained surveillance using more appropriate gravid traps and CDC CO2 light traps could improve sensitivity of vector collection and virus detection. AuthorsChuang, Ting-Wu, Knepper, Randall G., Stanuszek, William W., Walker, Edward D. and Wilson, Mark L. Year Published2011 PublicationJournal of Medical Entomology LocationsDOI10.1603/ME10138 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/21936324 |
| Weather and Land Cover Influences on Mosquito Populations in Sioux Falls, South Dakota | Chuang, Ting-Wu | 2011 |
KeywordsWest Nile virus, Culex tarsalis, Aedes vexans, weather, land cover, WNV AbstractThis study compared the spatial and temporal patterns of Culex tarsalis Coquillett and Aedes vexans Meigen populations and examined their relationships with land cover types and climatic variability in Sioux Falls, SD. Between 24 and 30 CDC CO2-baited light traps were set annually in Sioux Falls from May to September 2005–2008. Land cover data were acquired from the 2001 National Land Cover Dataset and the percentages of selected land cover types were calculated within a 600-m buffer zone around each trap. Meteorological information was summarized from local weather stations. Cx. tarsalis exhibited stronger spatial autocorrelation than Ae. vexans. Land cover analysis indicated that Cx. tarsalis was positively correlated with grass/hay, and Ae. vexans was positively correlated with wetlands. No associations were identified between irrigation and the host-seeking population of each species. Higher temperature in the current week and 2 wk prior and higher precipitation 3–4 wk before collection of host-seeking adult mosquitoes had positive influences on Cx. tarsalis abundance. Temperature in the current week and rainfall 2–3 wk before sampling had positive influences on Ae. vexans abundance. This study revealed the different influences of weather and land cover on important mosquito species in the Northern Great Plains region, which can be used to improve local vector control strategies and West Nile virus prevention efforts. AuthorsChuang, Ting-Wu, Hildreth, Michael B., Vanroekel, Denise L. and Wimberly, Michael C. Year Published2011 PublicationJournal of Medical Entomology LocationsDOI10.1603/ME10246 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/21661329 |
| Remote Sensing of Climatic Anomalies and West Nile Virus Incidence in the Northern Great Plains of the United States | Chuang, Ting-Wu | 2012 |
KeywordsWNV AbstractThe northern Great Plains (NGP) of the United States has been a hotspot of West Nile virus (WNV) incidence since 2002. Mosquito ecology and the transmission of vector-borne disease are influenced by multiple environmental factors, and climatic variability is an important driver of inter-annual variation in WNV transmission risk. This study applied multiple environmental predictors including land surface temperature (LST), the normalized difference vegetation index (NDVI) and actual evapotranspiration (ETa) derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) products to establish prediction models for WNV risk in the NGP. These environmental metrics are sensitive to seasonal and inter-annual fluctuations in temperature and precipitation, and are hypothesized to influence mosquito population dynamics and WNV transmission. Non-linear generalized additive models (GAMs) were used to evaluate the influences of deviations of cumulative LST, NDVI, and ETa on inter-annual variations of WNV incidence from 2004-2010. The models were sensitive to the timing of spring green up (measured with NDVI), temperature variability in early spring and summer (measured with LST), and moisture availability from late spring through early summer (measured with ETa), highlighting seasonal changes in the influences of climatic fluctuations on WNV transmission. Predictions based on these variables indicated a low WNV risk across the NGP in 2011, which is concordant with the low case reports in this year. Environmental monitoring using remote-sensed data can contribute to surveillance of WNV risk and prediction of future WNV outbreaks in space and time. AuthorsChuang, Ting-Wu and Wimberly, Michael C. Year Published2012 PublicationPLOS One LocationsDOI10.1371/journal.pone.0046882 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/23071656 |
| Emergence of Culex pipiens from Overwintering Hibernacula | Ciota, Alexander T. | 2011 |
KeywordsCulex pipiens, overwintering, mark–recapture, West Nile virus, WNV AbstractOverwintering populations of Culex pipiens, the principal enzootic vector of West Nile virus in the northeastern USA, were studied over 3 consecutive winters from 2006 to 2008, using mark–recapture techniques to determine when Cx. pipiens females began to disperse from overwintering hibernacula and how their survival influenced early season populations. In February of each year, Cx. pipiens were aspirated and marked using fluorescent powder; 4,067, 752, and 3,070 diapausing Cx. pipiens were marked in each successive year. Mosquitoes were then trapped from mid-April to early May of each year using 19 Centers for Disease Control and Prevention (CDC) light traps and 16 CDC gravid traps. A total of 348, 39, and 111 Culex mosquitoes were captured in the spring of 2006, 2007, and 2008, respectively. The number of mosquitoes marked in overwintering habitats is generally positively correlated with the number of mosquitoes recaptured in the early spring (linear regression, R2 = 0.79, P = 0.04), yet results also suggest that seasonal variations beyond overwintering population size are likely important in determining the success of emergent populations. A single marked Cx. pipiens was captured in both 2006 and 2008. In 2006, the mosquito was captured 0.5 km from its overwintering site while in 2008 the mosquito was captured 0.3 km from its overwintering site. In all study years, mosquitoes consistently began exiting overwintering hibernacula the 3rd week of April, yet evidence of earlier exodus was observed in 2007, when outside temperatures were significantly higher in preceding days and months. AuthorsCiota, Alexander T., Drummond, Cori L., Drobnack, Jason, Ruby, Meghan A., Kramer, Laura D. and Ebel, Gregory D. Year Published2011 PublicationJournal of the American Mosquito Control Association LocationsDOI10.2987/8756-971X-27.1.21 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/21476444 |
| 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 |
| SUSCEPTIBILITY OF GREATER SAGE-GROUSE TO EXPERIMENTAL INFECTION WITH WEST NILE VIRUS | Clark, Larry | 2006 |
KeywordsCentrocercus urophasianus, experimental infection, greater sage-grouse, vaccine, West Nile virus, WNV 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 (103.2 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 106.4 PFUs/ml (±100.2 PFUs/ml, standard error of the mean [SEM]). Virus was shed cloacally and orally. Four of the five vaccinated grouse died, but survival time was increased (50% survival=9.5 days), with 1 grouse surviving to the end-point of the experiment (14 days) with no signs of illness. Mean peak viremia for the vaccinated birds was 102.3 PFUs/ml (±100.6 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. AuthorsKlenk, Kaci, Bowen, Richard, Clark, Larry, Hall, Jeffrey, McLean, Robert, Dunbar, Michael and Smeraski, Cynthia A. Year Published2006 PublicationJournal of Wildlife Diseases LocationsDOI10.7589/0090-3558-42.1.14 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16699144 |
| Mosquito and Arbovirus Activity During 1997–2002 in a Wetland in Northeastern Mississippi | Cupp, E. W. | 2004 |
KeywordsSaint Louis encephalitis, eastern equine encephalomyelitis virus, Culex erraticus, Culiseta melanura, blood meal identification, WNV AbstractThe species composition and population dynamics of adult mosquitoes in a wetland near Iuka, MS, were analyzed over a 6-yr period (1997–2002) and reverse transcription-polymerase chain reaction (PCR) detection rates of arboviruses determined during five of those years. Blood meals of three likely vector species were identified using a PCR-based method that allows identification of the host to species. Culex erraticus (Dyar & Knab) composed 51.9% of the population during the 6-yr period with 295 females collected per trap night. Eastern equine encephalomyelitis (EEE) virus was detected in six genera of mosquitoes [Coquillettidia perturbans (Walker), Culex restuans Theobald, Culex salinarius Coquillett, Culex erraticus (Dyar & Knab), Anopheles crucians Wiedemann, Anopheles quadrimaculatus Say, Aedes vexans (Meigen), Ochlerotatus triseriatus Say, and Psorophora ferox Humboldt) with positive pools occurring in 1998, 1999, and 2002. Culiseta melanura Coquillett occurred at a low level (<1%) and was not infected. Saint Louis encephalitis virus was detected once in a single pool of Cx. erraticus in 1998. Neither West Nile virus nor LaCrosse virus was found. Minimum infection rates per 1000 females tested of competent vectors of EEE virus were variable and ranged from 0.14 for Cx. erraticus to 40.0 for Oc. triseriatus. Thirty-nine species of birds were identified in the focus with blood-engorged mosquitoes found to contain meals (n = 29) from eight avian species. The majority of meals was from the great blue heron, Ardea herodias L. (n = 55%), but when bird abundance data were adjusted for avian mass, the brown-headed cowbird, Molothrus ater (Boddaert); blue jay, Cyanocitta cristata (L.); and northern mockingbird, Mimus polyglottos (L.), were overrepresented as hosts. AuthorsCupp, E. W., Tennessen, K. J., Oldland, W. K., Hassan, H. K., Hill, G. E., Katholi, C. R. and Unnasch, T. R. Year Published2004 PublicationJournal of Medical Entomology LocationsDOI10.1603/0022-2585-41.3.495 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/15185956 |
| Liver metal concentrations in Greater Sage-grouse (Centrocercus urophasianus) | Dailey, Rebecca N. | 2008 |
Liver metal concentrations in Greater Sage-grouse (Centrocercus urophasianus)KeywordsCentrocercus urophasianus, ICP-MS, liver, metals, sage-grouse AbstractGreater Sage-grouse (Centrocercus urophasianus) are a species of concern due to shrinking populations associated with habitat fragmentation and loss. Baseline health parameters for this species are limited or lacking, especially with regard to tissue metal concentrations. To obtain a range of tissue metal concentrations, livers were collected from 71 Greater Sage-grouse from Wyoming and Montana. Mean SE metal concentrations (mg/kg wet weight) in liver were determined for vanadium (V) (0.12 +/- 0.01), chromium (Cr) (0.50 +/- 0.02), manganese (Mn) (2.68 +/- 0.11), iron (Fe) (1,019 +/- 103), nickel (Ni) (0.40 +/- 0.04), cobalt (Co) (0.08 +/- 0.02), copper (Cu) (6.43 +/- 0.40), mercury (Hg) (0.30 +/- 0.09), selenium (Se) (1.45 +/- 0.64), zinc (Zn) (59.2 +/- 4.70), molybdenum (Mo) (0.93 +/- 0.07), cadmium (Cd) (1.44 +/- 0.14), barium (Ba) (0.20 +/- 0.03), and lead (Pb) (0.17 +/- 0.03). In addition to providing baseline data, metal concentrations were compared between sex, age (juvenile/adult), and West Nile virus (WNv) groups (positive/negative). Adult birds had higher concentrations of Ni and Cd compared to juveniles. In addition, Zn and Cu concentrations were significantly elevated in WNv-positive birds. AuthorsDailey, Rebecca N.; Raisbeck, Merl F.; Slemion, Roger S.; Cornish, Todd E. Year Published2008 PublicationJournal of Wildlife Diseases Locations |
| Bird-Baited Traps for Surveillance of West Nile Mosquito Vectors: Effect of Bird Species, Trap Height, and Mosquito Escape Rates | Darbro, Jonathan M. | 2006 |
KeywordsWest Nile virus, house sparrow, chicken, Culex p. pipiens, Culex restuans, WNV AbstractHost-seeking mosquitoes were sampled in bird-baited traps at four sites in New York state in 2003–2004. Trap placement and efficacy of chickens, Gallus gallus domesticus L., as bait compared with house sparrows, Passer domesticus L., an important reservoir of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), was evaluated. Each site had a chicken-baited trap near ground level (≈1.5 m) and in the tree canopy (≈9 m), and a house sparrow-baited trap at ground level and canopy level. Each trap allowed mosquito access to birds on one end, and an inner mesh screen blocked bird access on the other end. The two most abundant mosquitoes, Culex restuans Theobald and Culex pipiens pipiens L., were differentiated using molecular characters. In 2003, Cx. restuans and Cx. p. pipiens made up 88% of total mosquito catch. In 2004, Cx. restuans comprised 43% of total catch and Cx. p. pipiens comprised 33%. The remaining species representing at least 1% of total catch were Ochlerotatus trivittatus (Coquillett), Coquilletidia perturbans (Walker), and Culiseta morsitans (Theobald). Capture rates were similar for chicken and house sparrow-baited traps; however, significantly more mosquitoes were captured in the canopy for both bird species. Cx. restuans preferred canopy traps, whereas equal numbers of Cx. p. pipiens were captured at ground and canopy levels. Mosquitoes were more likely to escape (74%) when excluded from birds than when allowed free access to birds (54%). Sentinel bird surveillance for WNV can be improved by trapping in the tree canopy in addition to ground level to capture the most important avian vectors. AuthorsDarbro, Jonathan M. and Harrington, Laura C. Year Published2006 PublicationJournal of Medical Entomology Locations- Tompkins County, New York state. Four different field sites were sampled and included dairy farm hedgerow (42° 26.501′ N 076° 25.889′ W), nature trail (42° 28.532′ N 076° 27.044′ W), golf course (42° 27.486′ N 076° 27.594′ W), and private residence (42° 26.924′ N 076° 25.757′ W) (42.442, -76.431)
- Tompkins County, New York state. Four different field sites were sampled and included dairy farm hedgerow (42° 26.501′ N 076° 25.889′ W), nature trail (42° 28.532′ N 076° 27.044′ W), golf course (42° 27.486′ N 076° 27.594′ W), and private residence (42° 26.924′ N 076° 25.757′ W) (42.476, -76.451)
- Tompkins County, New York state. Four different field sites were sampled and included dairy farm hedgerow (42° 26.501′ N 076° 25.889′ W), nature trail (42° 28.532′ N 076° 27.044′ W), golf course (42° 27.486′ N 076° 27.594′ W), and private residence (42° 26.924′ N 076° 25.757′ W) (42.458, -76.46)
- Tompkins County, New York state. Four different field sites were sampled and included dairy farm hedgerow (42° 26.501′ N 076° 25.889′ W), nature trail (42° 28.532′ N 076° 27.044′ W), golf course (42° 27.486′ N 076° 27.594′ W), and private residence (42° 26.924′ N 076° 25.757′ W) (42.449, -76.429)
DOI10.1603/0022-2585(2006)043[0083:BTFSOW]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/16506452 |
