Spatiotemporal Arboviral Surveillance in Florida

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1. Spatiotemporal Arboviral Surveillance in Florida - Tracking West Nile Virus Using GIS and Animation Gregory Ross Florida Medical Entomology Laboratory Vero Beach, Florida
2. 2001 to 2004 = 175 Human Cases 622 Equines Cases 2001 to 2004 = 4 Human Cases 294 Equines Cases Eastern Equine Encephalitis (EEE) West Nile Virus (WNV) St. Louis Encephalitis (SLE) Viruses mosquitoes transmit are referred to as arboviruses Introduction Arboviruses in Florida Highlands J Virus (HJV)
3. Vector Host Arboviral Amplification Cycle Amplification Host Spillover / Dead-end Hosts Jan – Mar = Maintenance Phase Apr - Jun = Amplification Phase Jul – Sep = Early Transmission Phase Oct - Dec = Late Transmission Phase
4. Sentinel Chicken Flocks are primary surveillance tool in Florida. Flocks have been in continuous use since 1978 in some counties. Flocks typically consist of 6 chickens in an open air cage located in suspected areas of arboviral transmission. Located at a permanent site. Flocks are tested weekly for presence of encephalitis antibodies in blood (SEROCONVERSION.) Preliminary test results are available within 2 to 5 days of blood being drawn. Encephalitis antibodies are not present at detectable levels until 10 to 16 days after transmission to chicken by an infected mosquito. Equates to a 12 to 21 day temporal lag effect between arboviral transmission periods and data availability for decision makers. Arboviral Surveillance in Florida
5. 289 Sites with Positive Seroconversions from 2000 to 2004 319 Sentinel Chicken Sites in Florida (2004) - Currently present in 40 of 67 Counties in Florida Geographic Distribution of Sentinel Chicken Flocks Spatiotemporal arboviral transmission attributes of West Nile and EEE are different and must be monitored closely to determine risk of transmission to humans. Spatially, EEE tends to be confined to northern Florida, while WNV is found from the Panhandle to Miami. Temporally, EEE is more frequently reported during the spring and fall months, while WNV is present throughout the year and is spatially more abundant during the summer months.
6. CDC / USGS Map Florida Sentinel Chicken Seroconversion Activity 2003 Typical Visualization of Sentinel Flock Data Florida DOH Sentinel Chicken Seroconversion Activity 08/22/2003
7. County level and point based maps serve a purpose but are not ideal. Real arboviral transmission patterns are found somewhere in between. Better Spatial Visualization Better Temporal Visualization Eliminate or condense temporal lag effect. Alignment with spatial data. Make it “Real-Time” or as close as possible, to enable decision makers. Better Analysis Techniques Raster layers to enable better GIS spatial and temporal analysis. Enable statistical analysis, including spatial and temporal confidence levels and degrees of certainty. Incorporate mathematical models with spatial and statistical analysis. Creation of Arboviral Transmission Pattern Prediction / Human Risk Analysis maps. Arboviral Surveillance / Visualization Areas That Need Improvement
8. Interpolated Arboviral Transmission Maps Florida Sentinel Chicken Seroconversion Activity from 08/03/2003 to 08/09/2003 West Nile EEE WN/EEE >1 Seroconversion 0 Seroconversions Seroconversion data entered into a geodatabase. ESRI ArcGIS Software used for interpolation. Tension Spline with Weighting to produce 53 interpolated layers for WN, EEE, and WN/EEE at a 1 km resolution Visually normalized to represent areas of arboviral transmission. Images export for use in Macromedia Flash MX. Process is semi-automated through VBA code.
9. AAS Visualization Challenge Honorable Mention Science, Volume 305, September 24, 2004 http://mosquito.ifas.ufl.edu/Surveillance_Videos.htm
10. The spatial and temporal aspects of arboviral transmission in Florida are more easily monitored and understood. Alignment of spatial and temporal transmission aspects, reducing the temporal lag effect. Speed and Portability. Animation size is small and can be produce quickly. Updates are posted weekly on http://mosquito.ifas.ufl.edu/. Better Spatial and Temporal Visualization Better Analysis of Arboviral Surveillance Data Arboviral Surveillance Animation Benefits Convey to mosquito control agencies and health departments throughout Florida that the most efficient use of the data generated in the sentinel surveillance programs is real-time analysis of the data. Show that the capability (software, hardware, experience, and knowledge) is present to improve arboviral surveillance techniques.
11. Use seroconversion rates for each sentinel site instead of raw numbers. Develop long-term seroconversion rates for each site (spatially and temporally) for use in deviation comparisons. Develop a color-blind version. Increase resolution to county level instead of state level. Spatial and temporal analysis with other data layers (environmental, ecological, human populations). Increase user interactivity. Integrate with current mathematical models of arboviral transmission. Develop Human Risk Analysis animations. Arboviral Surveillance Animation Future Improvements