| Effects of Single and Multiple Applications of Mosquito Insecticides on Nontarget Arthropods | Davis, Ryan S. | 2008 |
KeywordsMosquito control, adulticide, larvicide, ecological risk, nontarget organisms, West Nile virus, WNV AbstractMosquito management plans have been implemented in the United States and globally to manage mosquito vectors of West Nile virus and many other diseases. However, there is public concern about ecological risks from using insecticides to manage mosquitoes. Two studies were conducted during the late summers of 2004 through 2006 at Benton Lake National Wildlife Refuge near Great Falls, MT. The first experiment was conducted in 2004 and 2005 to assess acute impacts of mosquito adulticides (permethrin and d-phenothrin) and larvicides (Bacillus thuringiensis israelensis and methoprene) on nontarget aquatic and terrestrial arthropods after a single application. The second experiment was conducted in 2005 and 2006 to assess longer-term impacts of permethrin on nontarget terrestrial arthropods after multiple repeated applications. For aquatic samples, in the first study, no overall treatment effects were observed despite a potentially deleterious effect on amphipods on sample date 1 in 2004. During the same study, 1 of 54 responses had a significant overall treatment effect for sticky-card samples. Many of the responses for sticky-card samples suggested significant time effects and time × treatment effects. Three response variables were associated with fewer individuals present in the insecticide-treated plots in a multivariate analysis. For the multiple-spray study conducted in 2005 and 2006, 6 of the response variables collected via sticky cards exhibited significant overall treatment effects, but none was associated with fewer individuals in the insecticide-treated plots. None of the responses collected using sweep-net sampling suggested overall treatment effects. Time and time × treatment effects were prevalent in 2005, but no discernable pattern was evident. In general, nearly all of the responses evaluated for either study indicated few, if any, deleterious effects from insecticide application. AuthorsDavis, Ryan S. and Peterson, Robert K. D. Year Published2008 PublicationJournal of the American Mosquito Control Association LocationsDOI10.2987/5654.1 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/18666536 |
| Crow Deaths Caused by West Nile Virus during Winter | Dawson, Jennifer R. | 2007 |
KeywordsWNV AbstractIn New York, an epizootic of American crow (Corvus brachyrhynchos) deaths from West Nile virus (WNV) infection occurred during winter 2004–2005, a cold season when mosquitoes are not active. Detection of WNV in feces collected at the roost suggests lateral transmission through contact or fecal contamination. AuthorsEidson, Millicent, Ebel, Gregory D., Kramer, Laura D., Dawson, Jennifer R., Stone, Ward B., Young, David S., Galinski, David S., Pensabene, Jason P. and Franke, Mary A. Year Published2007 PublicationEmerging Infectious Diseases LocationsDOI10.3201/eid1312.070413 |
| Using Hydrologic Conditions to Forecast the Risk of Focal and Epidemic Arboviral Transmission in Peninsular Florida | Day, Jonathan F. | 2008 |
Keywordsarboviral epidemics, water table depth, hydrologic monitoring, St. Louis encephalitis virus, West Nile virus, WNV AbstractThe accurate forecasting and tracking of arboviral transmission is becoming increasingly critical for the early recognition and management of arboviral epidemics. Meteorological factors, especially rainfall and temperature, drive arboviral epidemics, but monitoring rainfall and temperature alone is not predictive of increased levels of vector-borne disease transmission. In Florida, model simulations of water table depth (WTD) provide a measure of drought, and they have been shown to provide an accurate forecast of arboviral transmission. Here, we tracked WTD in two peninsular Florida regions where focal West Nile virus (family Flaviviridae, genus Flavivirus, WNV) transmission was reported during 2004 and 2005. We compared the resulting WTD profiles with historical WTD simulations for Indian River County (IRC), FL, where two peninsular Florida St. Louis encephalitis virus epidemics had their epicenters in 1977 and 1990. In both of the regions where focal WNV transmission was reported during 2004 and 2005, the local WTD profiles approached the 1977 and 1990 IRC WTD profiles; however, differences in the local temporal sequence of hydrologic conditions were observed. These differences seem in part to explain why the focal WNV transmission during 2004 and 2005 failed to reach epidemic levels in peninsular Florida. These findings suggest that hydrologic monitoring, specifically WTD, may help determine the geographic extent, timing, and intensity of WNV transmission. We speculate that a more precise sequence of drought and wetting, including a secondary summer drying and wetting cycle, as occurred in IRC during 1977 and 1990, may provide the optimal hydrologic conditions for the expansion of an arbovirus outbreak from focal to epidemic. This study documents that monitoring hydrologic conditions, along with vector, avian amplification host, and virus population data, increases our ability to track and predict significant levels of arboviral transmission. AuthorsDay, Jonathan F. and Shaman, Jeffrey Year Published2008 PublicationJournal of Medical Entomology LocationsDOI10.1603/0022-2585(2008)45[458:UHCTFT]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/18533440 |
| Severe Winter Freezes Enhance St. Louis Encephalitis Virus Amplification and Epidemic Transmission in Peninsular Florida | Day, Jonathan F. | 2009 |
KeywordsWNV AbstractMosquito-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. AuthorsDay, Jonathan F. and Shaman, Jeffrey Year Published2009 PublicationJournal of Medical Entomology LocationsDOI10.1603/033.046.0638 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/19960704 |
| Factors Associated With the Risk of West Nile Virus Among Crows in New York State | DeCarlo, C. H. | 2011 |
KeywordsWNV AbstractWest Nile virus (WNV) is transmitted between avian hosts in enzootic cycles by a mosquito vector. The virus has significant disease effects on humans and equines when it bridges into an epizootic cycle. As the initial epidemic of WNV in 1999, perennial outbreaks in New York State suggest the local establishment of natural foci with perpetuation of the virus among susceptible hosts rather than reintroduction of the virus. The factors that play a role in the perpetuation of the virus are not fully understood. American crows (Corvus brachyrhynchos) are known to be highly susceptible to infection with the virus. We investigate the factors that put crows at risk of infection in Tompkins County, New York during the period of 2000-2008 in a case-control study. Cases were crow carcasses that were found dead and tested positive for WNV using real time reverse transcription or VecTest. Data on putative risk factors were collected and assessed for significance of association with the presence of WNV using logistic regression analysis to evaluate the significance of each factor while simultaneously controlling for the effect of others. The risk of a crow carcass testing WNV positive varied with age, season of the year and ecological area where the carcass was found. Crows that were more than 1-year-old were four times more likely to be WNV positive in comparison to birds that were less than 1 year of age. It was three times more likely to find WNV positive carcasses in residential areas in comparison to rural areas. The risk of testing WNV positive did not vary by sex of the crow carcasses. AuthorsDeCarlo, C. H., Clark, A. B., McGowan, K. J., Ziegler, P. E., Glaser, A. L., Szonyi, B. and Mohammed, H. O. Year Published2011 PublicationZoonoses and Public Health LocationsDOI10.1111/j.1863-2378.2010.01346.x Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/20707862 |
| Landscape, demographic, entomological, and climatic associations with human disease incidence of West Nile virus in the state of Iowa, USA | DeGroote, John P | 2008 |
KeywordsWNV AbstractBackground
West Nile virus (WNV) emerged as a threat to public and veterinary health in the Midwest United States in 2001 and continues to cause significant morbidity and mortality annually. To investigate biotic and abiotic factors associated with disease incidence, cases of reported human disease caused by West Nile virus (WNV) in the state of Iowa were aggregated by census block groups in Iowa for the years 2002–2006. Spatially explicit data on landscape, demographic, and climatic conditions were collated and analyzed by census block groups. Statistical tests of differences between means and distributions of landscape, demographic, and climatic variables for census block groups with and without WNV disease incidence were carried out. Entomological data from Iowa were considered at the state level to add context to the potential ecological events taking place.
Results
Numerous statistically significant differences were shown in the means and distributions of various landscape and demographic variables for census block groups with and without WNV disease incidence. Census block groups with WNV disease incidence had significantly lower population densities than those without. Landscape variables showing differences included stream density, road density, land cover compositions, presence of irrigation, and presence of animal feeding operations. Statistically significant differences in the annual means of precipitations, dew point, and minimum temperature for both the year of WNV disease incidence and the prior year, were detected in at least one year of the analysis for each parameter. However, the differences were not consistent between years.
Conclusion
The analysis of human WNV disease incidence by census block groups in Iowa demonstrated unique landscape, demographic, and climatic associations. Our results indicate that multiple ecological WNV transmission dynamics are most likely taking place in Iowa. In 2003 and 2006, drier conditions were associated with WNV disease incidence. In a significant novel finding, rural agricultural settings were shown to be strongly associated with human WNV disease incidence in Iowa. AuthorsDeGroote, John P, Sugumaran, Ramanathan, Brend, Sarah M, Tucker, Brad J and Bartholomay, Lyric C Year Published2008 PublicationInternational Journal of Health Geographics LocationsDOI10.1186/1476-072X-7-19 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/18452604 |
| Abundance of West Nile virus mosquito vectors in relation to climate and landscape variables | Deichmeister, Jayne M. | 2011 |
KeywordsWNV AbstractIt is currently unclear if the potential for West Nile virus transmission by mosquito vectors in the eastern United States is related to landscape or climate factors or both. We compared abundance of vector species between urban and suburban neighborhoods of Henrico County, VA, in relation to the following factors: temperature, precipitation, canopy cover, building footprint, and proximity to drainage infrastructure. Mosquitoes were collected throughout the 2005, 2006, and 2007 seasons and tested for West Nile virus (WNV) in pools of 10-50. Test results of mosquito pools were compared to average site abundance from 37 sites in Henrico County, VA; abundance was then examined in relation to ecological variables. Urban infrastructure was positively correlated with the abundance of Culex pipiens L./Cx. restuans, and our findings implicate combined sewer overflow systems as large contributors to Culex vector populations. No measure of urbanization examined in our study was correlated with Aedes albopictus abundance. Our study showed that certain landscape variables identified using Geographic Information Systems are valuable for predicting primary WNV vector abundance in Virginia, and that temperature along with low precipitation are strong predictors of population growth. Our results support other regional studies that found WNV proliferates under drought conditions. AuthorsDeichmeister, Jayne M. and Telang, Aparna Year Published2011 PublicationJournal of Vector Ecology LocationsDOI10.1111/j.1948-7134.2011.00143.x Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/21635644 |
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ASSOCIATIONS BETWEEN TWO MOSQUITO POPULATIONS AND WEST NILE VIRUS IN HARRIS COUNTY, TEXAS, 2003–06
1
| DENNETT, JAMES A. | 2007 |
KeywordsWest Nile virus, Culex quinquefasciatus, Aedes albopictus, gravid trap, minimum infection rate, Cyanocitta cristata, blue jay, blood meal analysis, WNV AbstractAssociations between Culex quinquefasciatus, Aedes albopictus and West Nile virus (WNV) activity, temperature, and rainfall in Harris County, Texas 2003–06 are discussed. Human cases were highly correlated to Cx. quinquefasciatus (r = 0.87) and Ae. albopictus (r = 0.78) pools, blue jays (r = 0.83), and Ae. albopictus collected (r = 0.71), but not Cx. quinquefasciatus collected (r = 0.45). Human cases were associated with temperature (r = 0.71), not rainfall (r = 0.29), whereas temperature correlated with Ae. albopictus and Cx. quinquefasciatus collections (r = 0.88 and 0.70, respectively) and Cx. quinquefasciatus pools (r = 0.75), but not Ae. albopictus pools (r = 0.55). Both species (collections and pools) and blue jays were weakly correlated (r ≤ 0.41) with rainfall, but blue jays were better correlated with Cx. quinquefasciatus pools (r = 0.87), compared with Ae. albopictus pools (r = 0.67), Ae. albopictus collections (r = 0.69), and Cx. quinquefasciatus collections (r = 0.46). Peak minimum infection rate for Cx. quinquefasciatus (4.55), and Ae. albopictus (4.41) was in August with highest human cases (17.87), blue jays (55.58), and temperature (29.01°C). Between both species, blood meal analysis indicated 68.18% of Cx. quinquefasciatus mammalian hosts were dog, while 22.72% were human, whereas Ae. albopictus had higher human (44.44%) but fewer dog hosts (22.22%). Ten bird species were identified as hosts for Cx. quinquefasciatus, with northern cardinal and blue jay representing 26.66% and 20.00%, respectively. No bird feeding activity was observed in Ae. albopictus. The earliest and latest human blood meal occurred in May (Ae. albopictus) and November (Cx. quinquefasciatus); 66.66% of human host identifications between both species occurred in October–November, after the seasonal human case peak. Based upon our data, WNV activity in both mosquito species warrants further investigation of their individual roles in WNV ecology within this region. AuthorsTesh, Robert B., Siirin, Marina, Randle, Yvonne, Guzman, Hilda, Wuithiranyagool, Taweesak, Bueno, Rudy, PARSONS, RAY E., DENNETT, JAMES A., BALA, ADILELKHIDIR, SARGENT, CHRISTOPHER B., HASSAN, HASSAN K., REYNA-NAVA, MARTIN and UNNASCH, THOMAS R. Year Published2007 PublicationJournal of the American Mosquito Control Association LocationsDOI10.2987/8756-971X(2007)23[264:ABTMPA]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/17939505 |
| 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 |
| COMPARISON OF MOSQUITO TRAPPING METHOD EFFICACY FOR WEST NILE VIRUS SURVEILLANCE IN NEW MEXICO | DiMenna, Mark A. | 2006 |
KeywordsMosquitoes, trapping methods, New Mexico, Rio Grande, West Nile virus, WNV AbstractAs part of the West Nile virus surveillance program for the state of New Mexico, 13 sites along the Rio Grande River were sampled for mosquitoes during spring and summer 2003. We evaluated 3 different trapping procedures for their effectiveness at capturing selected species of mosquitoes. The 3 methods used were a dry ice-baited Centers for Disease Control and Prevention (CDC) light trap set 1.5 m above the ground (standard method), a CDC light trap suspended within the forest canopy, and a gravid trap set on the ground. Thirteen sites were sampled for 10 1-night periods biweekly from May through September. The relative numbers of captured Culex tarsalis, Cx. salinarius, Cx. quinquefasciatus, and Aedes vexans as well as the numbers of total recorded captures of all species were compared for each trapping method. Significant differences were observed for each species by location and by trapping method. Culex tarsalis was most commonly caught in canopy or standard CDC traps, especially in cottonwood bosque. Culex salinarius was found most frequently in association with marshy water, and was most often caught in gravid or standard light traps. Culex quinque-fasciatus was captured almost exclusively in gravid traps within urban areas. Aedes vexans was primarily sampled in standard CDC light traps and found most frequently in wooded areas near floodplains. With the exception of Cx. quinquefasciatus, no species was collected significantly more frequently in gravid or canopy traps than in the standard CDC light trap. Our findings do not support altering the methods currently used in New Mexico, namely, the use of 1.5-m CDC light traps and gravid traps. An increased use of gravid traps seems to be warranted in monitoring urban vector populations (specifically Cx. quinquefasciatus and Cx. salinarius) that may be involved in human transmission. 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 the American Mosquito Control Association Locations- Espanola, NM (35.991, -106.082)
- Bernalillo, NM (35.0178, -106.629)
- Los Lunas, NM (34.8062, -106.733)
- Belen, NM (34.6628, -106.776)
- Velarde, NM (36.1673, -105.968)
- San Acacia, NM (34.2553, -106.899)
- Santa Fe, NM (35.687, -105.938)
- Bosque del Apache Wilderness (Chupadera Unit), Socorro, NM (33.8381, -106.939)
- Arroyo Hondo, NM (36.5361, -105.67)
- Pilar, NM (36.2691, -105.782)
- Los Alamos, NM (35.8881, -106.307)
DOI10.2987/8756-971X(2006)22[246:COMTME]2.0.CO;2 Additional Information:http://www.ncbi.nlm.nih.gov/pubmed/17019770 |
