Thesis (M.Sc.)--York University, 2007. Graduate Programme in Mathematics and Statistics. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR29300

Thesis (Ph. D.)--Michigan State University. Fisheries and Wildlife, 2008. / Title from PDF t.p. (Proquest, viewed on Aug. 20, 2009) Includes bibliographical references. Also issued in print.

Thesis (M.S.)--Brock University, 2009. / Includes bibliographical references (leaves 121-136).

Objective: To develop an original survey on public attitudes, knowledge and practices on West Nile Virus (WNV), mosquitoes, and pesticides. We sought to gain insight on what personal protective behaviors (PPBs) are used by the public and whether the public is supportive of pesticide use in combating the threat of WNV. An effective WNV control program must take into account the public's attitudes regarding PPBs and what would influence their use of PPBs. The survey findings will be used to develop a new educational plan for the West Nile Virus Surveillance and Control Program of Delaware County. We sought to determine if knowledge and concern about one's personal risk of contracting WNV were driving forces in one's use of PPBs and support of pesticide use. Results: The sample population was highly informed on WNV and used many PPBs. Knowledge of WNV and concern about contracting WNV were not significant predictors of PPB use or pesticide support. However, odds ratios indicate an increased odds of being in the high PPB group with increasing knowledge. Knowing someone who has or has had WNV was a factor in PPB use, although the outcome of WNV infection is rarely reported. Older age predicted greater PPB use while higher education predicted a lack of support for pesticide use. Conclusion: Future surveys of the public knowledge will need to reach a more diverse population than that of the current study. It appears that many people are using PPBs despite not believing in their efficacy at preventing mosquito bites and WNV. Future studies should seek to identify what is motivating people to use these PPBs, besides knowledge of WNV and concern for their health. / Public Health

Nous avons cherché à mieux comprendre la situation épidémiologique du virus West Nile (VWN) en Tunisie. Nous avons tout d'abord produit une carte du risque de transmission du VWN aux équidés montrant un risque élevé dans de nombreuses régions, dépendant de facteurs environnementaux : zones humides et climat favorables aux populations d'oiseaux sauvages et de moustiques. Le taux élevé de séroprévalence observé chez les équidés est compatible avec l'hypothèse d'une circulation endémique du VWN sans exclure la possibilité d'introductions répétées.Une étude complémentaire a démontré l'exposition des oiseaux domestiques, péri-domestiques et sauvages au VWN et a permis d'établir un premier inventaire des espèces d'oiseaux les plus exposées, pouvant servir de base à un système de surveillance de l'avifaune sauvage en Tunisie.Le suivi sérologique mensuel de poules sentinelles a permis de détecter la circulation du virus en fin de saison chaude (septembre, octobre) à proximité de zones humides pendant une période de forte activité des moustiques et d‘abondance des oiseaux sauvages. L'occurrence simultanée de cas humains de fièvre West Nile (FWN) laisse penser qu'un système de poules sentinelles serait utile pour une alerte précoce de recrudescence de l'activité du VWN.A l'issue de ce travail, nous proposons des pistes pour un système de surveillance multidisciplinaire de la FWN, adapté au contexte tunisien, et devant permettre la détection précoce de toute circulation virale. / Our investigations aimed at clarifying some aspects of the West Nile virus (WNV) epidemiological situation in Tunisia, and in particular at identifying areas at high risk of WNV circulation. A major achievement was the establishment of a risk map for the transmission of WNF in horses. This map shows that the risk of transmission strongly depends on environmental factors: increased risk associated to wetlands proximity and climatic factors favourable to wild birds and mosquitoes. The high seroprevalence observed in horses is compatible with an endemic circulation of WNV without excluding the possibility of repeated introductions.Another study in birds showed the exposure of domestic, wild resident and migratory birds to WNV, and helped establishing an initial inventory of bird species most exposed to WNV. These studies can serve as a basis for a monitoring system of wild birds in Tunisia.A system of monthly follow-up of sentinel chickens detected virus circulation at the end of the hot season (September, October), near wetlands and during a period of high mosquito activity, and abundance of wild birds. The simultaneous occurrence of human cases of WNF brought us to suggest that active surveillance in sentinel chickens would be useful for early warning of increased activity of WNV. This work allows us to propose trails for a WNV multidisciplinary monitoring system adapted to the Tunisian situation, enabling early detection of viral circulation.

West Nile Virus (WNV) first appeared in Texas equids during June 2002. It has since spread rapidly across the state and apparently become endemic. Data from outbreaks occurring between 2002 and 2004 were analyzed to determine hotspots of equine WNV disease, identify environmental factors associated with outbreaks, and to create risk maps of locations with horses at a higher risk of the disease. Kriging was used to model the smoothed WNV attack rates, and interpolated rates were mapped to describe the spatial distribution of WNV disease risk in Texas. A retrospective time-space analysis using a Poisson model was conducted on each year’s data to identify clusters with high attack rates. The resulting overlapping yearly clusters were considered areas of hyperendemicity (hotspots). The counties identified as hotspots included Hockley, Lubbock, and Lynn (primary cluster) and Leon and Roberstson (secondary cluster). Environmental and geographic features were added to the disease maps and analyzed to determine possible environmental factors associated with outbreaks. Locations in close proximity to lakes, bird breeding routes, migratory flyway zones, crop farm and agricultural land, and all dense vegetation were found to be important environmental predictors. Finally, risk maps were created that combined surveillance data on WNV positive mosquito collections and wild bird WNV cases with previously identified environmental risk factors to predict areas of high occurrence of WNV. These risk maps could be used to implement various preventative measures to reduce the transmission of WNV in the Texas equine industry.

Between the years 2006-2007, Harris County, located at the heart of the Houston metropolitan area, experienced a nearly 90% decline in the number of female mosquitoes which tested positive for the West Nile virus. Different theories exist as to why such a precipitous drop occurred and this study attempts to determine the extent to which climatic variability between the two years played a role. The Mosquito Control Division of Harris County Public Health and Environmental Services gathered the data on vectors and reservoirs. Then using GIS, spatial analysis, and geostatistical tools the vector and reservoir data was compared to climatic data to investigate any changes in viral distribution. Previous studies of the area until now have used a limited amount of climatic data; this study seeks to improve the resolution of climatic data analyzed. A higher resolution of data was achieved by including as-of-yet unused data from a network of over 150 gauges maintained by various state and local agencies in addition to previously used data from NOAA COOP stations. Using this dense network of station's values for precipitation, temperature and other climatic variables were interpolated for all of Harris County and used in the analysis. Based on results, water availability was the most likely out of all the climatic variables to the precipitous drop of West Nile virus positive female mosquitoes from 2006-2007. Correlations between all climatic variables and mosquito abundance and West Nile virus positives showed mixed results compared to a previous study in the same area.

West Nile Virus (WNV) first appeared in Texas equids during June 2002. It has since spread rapidly across the state and apparently become endemic. Data from outbreaks occurring between 2002 and 2004 were analyzed to determine hotspots of equine WNV disease, identify environmental factors associated with outbreaks, and to create risk maps of locations with horses at a higher risk of the disease. Kriging was used to model the smoothed WNV attack rates, and interpolated rates were mapped to describe the spatial distribution of WNV disease risk in Texas. A retrospective time-space analysis using a Poisson model was conducted on each year's data to identify clusters with high attack rates. The resulting overlapping yearly clusters were considered areas of hyperendemicity (hotspots). The counties identified as hotspots included Hockley, Lubbock, and Lynn (primary cluster) and Leon and Roberstson (secondary cluster). Environmental and geographic features were added to the disease maps and analyzed to determine possible environmental factors associated with outbreaks. Locations in close proximity to lakes, bird breeding routes, migratory flyway zones, crop farm and agricultural land, and all dense vegetation were found to be important environmental predictors. Finally, risk maps were created that combined surveillance data on WNV positive mosquito collections and wild bird WNV cases with previously identified environmental risk factors to predict areas of high occurrence of WNV. These risk maps could be used to implement various preventative measures to reduce the transmission of WNV in the Texas equine industry.

Thesis (M.Sc.)--York University, 2008. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 56-75). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38744

Thesis (M.S. in entomology)--Washington State University, August 2009. / Title from PDF title page (viewed on Aug. 12, 2009). "Department of Entomology." Includes bibliographical references (p. 65-68).