Department of Geography College of Earth and Mineral Sciences

1. Department of Geography College of Earth and Mineral Sciences Identifying the Spatially Dynamic Variables Affecting the Distribution of West Nile Virus in Pennsylvania GEOG – 596A, Summer 2013 Mark Brady Advisor: Dr. Justine Blanford

2. Department of Geography College of Earth and Mineral Sciences Project Outline Background Origin in North America Health Effects Enzootic Cycle Environmental Variables Methods Geographically Weighted Regression Expected outcomes Identification of Explanatory Variables Predictive Model of WNV Distribution Timeline Acknowledge

3. Department of Geography College of Earth and Mineral Sciences What is West Nile Virus ? WNV was first isolated in Uganda in 1937 Appeared on the North American Continent in 1999 (New York, isolated from a Flamingo in the Bronx Zoo) WNV had spread to the west coast within 4 years Since 1999 WNV has been detected in all of the Lower 48 States

4. What is West Nile Virus? Department of Geography College of Earth and Mineral Sciences Avian Host Typical WNV Transmission Cycle Incidental Hosts WNV Vector Avian Host

5. 1999 2000 Department of Geography College of Earth and Mineral Sciences 2001 2002 2003 2004

6. Department of Geography College of Earth and Mineral Sciences Why is West Nile Virus a Problem ? Human infection with WNV may result in serious illness and in extreme cases, death WNV is an invasive exotic species in North America 50% reduction in bird populations, particularly among Corvids (Crows and Jays)

7. Department of Geography College of Earth and Mineral Sciences West Nile Virus Infection - Symptoms and Prognosis +/- 80% of people infected with WNV will develop no symptoms. Symptoms include: fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash, with fatigue and weakness that may last for weeks or months < 1% of human infections are fatal (e.g. neurologic illness such as encephalitis or meningitis) and can lead to death

8. WNV Impacts on Human Health Department of Geography College of Earth and Mineral Sciences Total Infected: 37,088 Total Deaths: 1,549

9. Anthropogenic and Environmental Factors Affecting WNV Department of Geography College of Earth and Mineral Sciences Kilpatrick (2011). Globalization, Land Use, and the Invasion of West Nile Virus, Sciences

10. Factors Affecting WNV Department of Geography College of Earth and Mineral Sciences Temperature Source : Reisen et al. 2006 J Med Entomol 43:309-317 Precipitation Source : Blanford et al. 2012, Submitted

11. Anthropogenic and Environmental Factors Affecting WNV - Landuse Department of Geography College of Earth and Mineral Sciences Kilpatrick (2011).

12. Literature Review

13. Factors affecting WNV Department of Geography College of Earth and Mineral Sciences Spatial and temporal effects - Modelling at weekly/monthly/bimonthly etc. to best capture population dynamics Land use – Urban vs. Rural Temperature – affects virus transmission and population abundance Rainfall – affects population abundance and availability of breeding sites Vector species and composition (Culex species: Cx tarsalis, Cx pipiens, Cx restuans, Cx salinarius)

14. Department of Geography College of Earth and Mineral Sciences Challenges Modeling WNV Environmental parameters are not stationary, they vary spatially in occurrence and intensity The relationship between parameters influencing WNV occurrence vary spatially The competence and abundance of vectors vary spatially Host abundance varies spatially Question remains… What key factors are important for predicting WNV? Do these vary geographically?

15. West Nile Virus in Pennsylvania Department of Geography College of Earth and Mineral Sciences WNV first detected in 2000 WNV PA has been collecting mosquitoes since 2000 Surveillance results used to guide mitigation efforts (larvicides, adulticides, breeding habitat removal) Over 35,000 locations sampled statewide Calculate MIR (Infection Rates: Proportion of mosquitoes +ve WNV of all mosquitoes collected. Sampling sites are chosen based on nuisance complaints, past history, and staff experience No environmental data has been collected

16. Project Goals and Objectives Department of Geography College of Earth and Mineral Sciences Spatial and temporal dynamics of WNV are not well described for PA since no detailed analysis of PA data has been conducted. Explore complex interactions of a variety of factors that can influence disease dynamics. Identify the variables that best explain the distribution and abundance of WNV in Pennsylvania using Geographically Weighted Regression (GWR) Once identified, use the  GWR model to estimate WNV distribution and intensity statewide (compared to historical, normal, and projected input criteria)

17. Department of Geography College of Earth and Mineral Sciences 2001 2005 1999 2002 2006 2010 2003 2007 2011 1999 2008 2012

18. Important WNV Vector Species in Pennsylvania Department of Geography College of Earth and Mineral Sciences Culexpipiens –Primary vector of WNV to humans. Often associated with urban and suburban areas. Preferred hosts are birds, but will feed on mammals, snakes, and reptiles when avian hosts are unavailable. Larval habitats are stagnant pools, sewage plants, artificial containers (tires, buckets, etc.). Tolerant of polluted water Culexrestuans – Competent vector for WNV. Often associated with urban and suburban areas, but known to occur in diverse range of habitats. Preferred hosts are birds, but will feed on mammals, amphibians, and reptiles when avian hosts are unavailable. Larval habitats are similar to Cx.Pipiens, but less tolerant of polluted water. Abundant early in season and amplification of WNV. Culexsalinarius – An opportunistic feeder that will readily feed on birds or mammals, therefore may be an important bridge vector for WNV. Larval habitats include temporary grassy pools and artificial containers, though this species prefers natural habitats to artificial habitats.

19. Proposed Methods Department of Geography College of Earth and Mineral Sciences Identify the variables that most affect the abundance, competence, and distribution of WNV in PA Overview of WNV in PA Analyze 6 years of data: 2003 and 2012 (high WNV incidence) 2006 and 2007 (mid WNV incidence) 2001 and 2011 (low WNV incidence) Identify key WNV locations over the years Identify temporal patterns of WNV (seasonality) Describe vector populations (spatial, temporal, species) Describe vector competence (spatial, temporal, species) Explore spatially varying relationships between WNV variables using GWR

20. Department of Geography College of Earth and Mineral Sciences Potentially Significant Variables Temperature – Min, Max, Mean, Duration Precipitation – Weekly/Monthly Sums and Means Land Uses – Percentages by Spatial Units Human Population Densities by Spatial Units Vectors – Populations and Distributions by Temporal and Spatial Units MIR – Mosquito Infection Rates

21. Data Sources Department of Geography College of Earth and Mineral Sciences Landuse Population Cadastral Units Watershed Boundaries Hydrography Precipitation Temperature Climate Normal Summaries Climate Forecasts Vector ID Vector Enumerations WNV Test Results Historical/Future Treatments

22. Proposed Methodology: Geographically Weighted Regression (GWR) Department of Geography College of Earth and Mineral Sciences Brunsdon, Fotheringham, and Charlton (1996) Geographically Weighted Regression: A Method for Exploring Spatial Nonstationarity Spatial Autocorrelation Tobler’s Law (1970) Extension of multivariate regression that allows regression models to vary spatially Allows the relationships between the independent variables to vary

23. Proposed Methodology: Geographically Weighted Regression (GWR) Department of Geography College of Earth and Mineral Sciences

24. ProposedMethodology: Geographically Weighted Regression (GWR) Department of Geography College of Earth and Mineral Sciences y = β +β x +ε 0 1 for i=1 … n b= Regression Coefficients y = Variable Estimates W= Weighting Coefficients

25. Proposed Methodology: Geographically Weighted Regression (GWR) Department of Geography College of Earth and Mineral Sciences Kernel Function - Defines the shape of the spatial weighting function (w) W = 1 W = 0 D *ArcMap uses a Gaussian function

26. Proposed Methodology: Geographically Weighted Regression (GWR) Department of Geography College of Earth and Mineral Sciences Adaptive Bandwidth Fixed Bandwidth

27. Proposed Methodology: Geographically Weighted Regression (GWR) Department of Geography College of Earth and Mineral Sciences Output feature class (estimates at regression points) Model coefficient rasters for each variable Diagnostic summary table Prediction output feature class (estimates at locations other than regression points)

28. Exploratory Analysis and Results Department of Geography College of Earth and Mineral Sciences Annual Land use Temperature (Mean) Population Density WNV +ve mosquitoes Adaptive Bandwidth 2003 Land use Temperature (Mean) Population Density WNV +ve mosquitoes Fixed Bandwidth Regression Coefficients

29. Exploratory Analysis and Results Department of Geography College of Earth and Mineral Sciences Annual Land use Temperature (Mean) Population Density WNV +ve mosquitoes Adaptive Bandwidth 2003 Land use Temperature (Mean) Population Density WNV +ve mosquitoes Fixed Bandwidth Estimate Standard Residuals

30. Exploratory Analysis and Results Department of Geography College of Earth and Mineral Sciences Annual Land use Temperature (Mean) Population Density WNV +ve mosquitoes Adaptive Bandwidth 2003 Land use Temperature (Mean) Population Density WNV +ve mosquitoes Fixed Bandwidth Estimate Residuals

31. Exploratory Analysis and Results Department of Geography College of Earth and Mineral Sciences Annual Land use Temperature (Mean) Population Density WNV +ve mosquitoes Adaptive Bandwidth 2003 Land use Temperature (Mean) Population Density WNV +ve mosquitoes Fixed Bandwidth Local R2 Statistic

32. Exploratory Analysis and Results Department of Geography College of Earth and Mineral Sciences Annual Landuse Temperature (Mean) Population Density WNV +ve mosquitoes Adaptive Bandwidth 2003 Landuse Temperature (Mean) Population Density WNV +ve mosquitoes Fixed Bandwidth Statistical Summary Tables

33. Expected Results Department of Geography College of Earth and Mineral Sciences A dataset of historical mosquito populations, competence, and species distribution merged with potentially relevant environmental data Identify the environmental variables best suited to explain the historical distribution and intensity of WNV in PA Develop a predictive GWR model using historical relationships between environmental variables and mosquito vectors, in order to estimate WNV response to future changes in climate, landuse, and human population dynamics Acknowledge

34. Department of Geography College of Earth and Mineral Sciences Project Timeline Conference Presentation 596 A Peer Review March 2014 596 A Literature review February 2014 January 2014 596 B Complete Data Analysis July 2013 May 2013 Cloud Server Class

35. Selected References Department of Geography College of Earth and Mineral Sciences Blanford, J. I., Blanford, S., Crane, R. G., Mann, M. E., Paaijmans, K. P., Schreiber, K. V., et al. (2013). Implications of temperature variation for malaria parasite development across Africa. Scientific Reports, 3 (1300). Brunsdon, C., Fotheringham, A. S., & Charlton, M. (1999). Some notes on parametric significance tests for geographically weighted regression. Journal of Regional Science, 39 (3), 497-524. Brunsdon, C., Fotheringham, A. S., & Charlton, M. E. (1996). Geographically weighted regression: a method for exploring spatial nonstationarity. Geographical Analysis, 28 (4), 281-298. Brunsdon, C., McClatchey, J., & Unwin, D. J. (2001). Spatial variation in the average rainfall - altitude relationship in Great Britain: an approach using geographically weighted regression. International Journal of Climatology, 21, 455-456. Charlton, M., & Fotheringham, A. S. (2009). Geographically Weighted Regression (White Paper). National University of Ireland Maynooth. Maynooth, Ireland: National Center for Geocomputation. PAWNVCP. (2013). Pennsylvania's West Nile Virus Control Program. Retrieved May 18, 2013, from http://www.westnile.state.pa.us/index.html Reisen, W. K., Fang, Y., & Martinez, V. M. (2006). Effects of temperature on the transmission of West Nile virus by Culex tarsalis (Diptera:Culicidae). Journal of Medical Entomology, 43 (2), 309-317.

36. Selected References Department of Geography College of Earth and Mineral Sciences Reisen, W. K., Thiemann, T., Barker, C. M., Lu, H., Carroll, B., Fang, Y., et al. (2010). Effects of warm winter temperature on the abundance and gonotrophic activity of Culex (Diptera:Culicidae) in California. Journal of Medical Entomology, 47 (2), 230-237. Ruiz, M. O., Tedesco, C., McTighe, T. J., Austin, C., & Kitron, U. (2004). Environmental and social determinants of human risk during a West Nile virus outbreak in the greater Chicago area, 2002. International Journal of Health Geographics, 3 (8). Kilpatrick, A. M. (2011). Globalization, Land Use, and the Invasion of West Nile Virus. Science, 334, 323-327. Kilpatrick, A. M., Daszak, P., Jones, M. J., Peter, P. M., & Kramer, L. D. (2006). Host heterogeneity dominates West Nile virus transmission. Proc Biol Sci, 273, 2327-2333. Kilpatrick, A. M., Fornseca, D. M., Ebel, G. D., Reddy, M. R., & Kramer, L. D. (2010). Spatial and temporal variation in vector competence of Culex pipiens and Culex restuans mosquitoes for West Nile virus. Am J Trop Med Hyg, 83 (3), 607-613. Kilpatrick, A. M., Meola, M. A., Robin, M. M., & Kramer, L. D. (2008). Temperature, viral genetics, and the transmission of West Nile virus by Culex pipiens mosquitoes. Plos Pathogens, 4 (6). Chaves, L. F., Hamer, G. L., Walker, E. D., Brown, W. M., Ruiz, M. O., & Kitron, U. D. (2011). Climatic variability and landscape heterogeneity impact urban mosquito diversity and vector abundance and infection. Ecosphere, 2 (6).

37. Acknowledgements Department of Geography College of Earth and Mineral Sciences Dr. Justine Blanford Michael Hutchinson - PA West Nile Virus Control Program Andrew Kyle - PA West Nile Virus Control Program James Haefner - PA West Nile Virus Control Program Matt Helwig - PA West Nile Virus Control Program Dr. Doug Miller Beth King

38. Questions Department of Geography College of Earth and Mineral Sciences