An Examination of Environmental Conditions Related to Localized Arboviral Transmission in Florida (Three Case Studies)

Presented at the Florida Mosquito Control Association Regional Short Course: Public Health Pest Control Training: Mosquito-borne Disease, GIS, and reports on selected mosquito species in Florida

1. An Examination of Environmental Conditions Related to Localized Arboviral Transmission in Florida (Three Case Studies) Gregory Ross, Jonathan Day, Roxanne Connelly Florida Medical Entomology Laboratory – UF/IFAS
2. Surveillance Tools Prediction Tools Factors that Drive Arboviral Epidemics Environmental Factors Amplification Host Virus Vector
3. Sentinel Chicken Flocks ~ 319 Sentinel Chicken Sites in Florida (2007) Currently present in 40 of 67 Counties in Florida Arboviral Transmission Surveillance Tool
4. CDC / USGS Map Florida Sentinel Chicken Seroconversion Activity 2003 Florida DOH Sentinel Chicken Seroconversion Activity 08/22/2003 Sentinel Chicken Seroconversions Visualization
5. Can we do it better?
7. What do we really know?
9. Spatial / Temporal Alignment Drought and Wetting Spring drought in peninsular Florida is the main driving factor that forces birds and mosquitoes together into focal amplification communities. Summer wetting is the main driving factor that allows for transmission outside of focal amplification areas. Naïve Bird Populations Mosquito Breeding Habitats Driving Environmental Factor
10. ≠ What do we really know? The rainfall pattern is as equally or even more important than the amount of rainfall!!
11. Arboviral Transmission Prediction Tools Three real-time environmental tools NEXt Generation RADar Rainfall Totals – NEXRAD Keetch-Byram Drought Index - KBDI Modeled Water Table Depth – MWTD
12. NWS Precipitation Analysis - NEXRAD Data is a byproduct of NWS operations at 12 River Forecast Centers and derives from a multisensor approach. Inputs include WSR-88D NEXRAD radar and ground rainfall gauge reports. Spatial resolution of 4 km2 and a temporal resolution of 60 minutes. Data is produced hourly by National Weather service across all of the continental United States. Data is available as a free download in either daily or hourly packages in different formats.
13. 8,870 KBDI data points across Florida NWS Precipitation Analysis - NEXRAD
14. NWS Precipitation Analysis - NEXRAD
15. Rain Gauges versus Doppler Radar
16. Site Comparison (Oct 1, 2008 to Sept 30,2009)
17. Rain Gauges are better than Doppler for accurate recording of actual amounts of rainfall in specific locations…choose their locations with a purpose. Doppler rainfall totals are extremely precise and may be better for picking up trace amounts than Rain Gauges. Rain Gauges may over-estimate regional rainfall amounts. Doppler is better suited for broad, regional rainfall estimations. NWS Precipitation Analysis - NEXRAD
18. Keetch-Byram Drought Index - KBDI Continuous reference scale for estimating the dryness of the soil and duff layers. The scale ranges from 0 (no moisture deficit) to 800 (extreme moisture deficit). Inputs include temperature and rainfall. KBDI originally developed by John Keetch and George Byram for the USDA. 8,870 KBDI data points across Florida Data is produced daily by Florida Division of Forestry across all of the state and much of the southeast. Spatial resolution of 4 km2 and a temporal resolution of 24 hours.
19. Keetch-Byram Drought Index - KBDI
20. Integrated measure of near surface soil wetness. Inputs include precipitation, temperature, soil and vegetation types, and evapotranspiration distributed by NOAA through its Global Energy and Water Cycle Experiment Project. Spatial resolution of 0.125° (~11 km2) and a temporal resolution of 24 hours. Model developed by Jeffery Shaman (Oregon State University) and Jonathan Day (University of Florida). Modeled Water Table Depth – MWTD 589 MWTD data points across peninsular Florida MWTD only available for southern peninsular Florida due to the required topography restraints of the model. Funding needed to develop a northern Florida model.
21. Initial Dry Down Initial Wetting Secondary Dry Down Secondary Wetting (May – June) (June - July) (July - August) (August - September) Low areas (ditched, furrows, sinkholes) Culex nigripalpus ovisposition sites Water Table 1.6 meters below surface Water Table 1.0 meters below surface Water Table 1.3 meters below surface Water Table 0.8 meters below surface Modeled Water Table Depth – MWTD
22. Modeled Water Table Depth
23. Modeled Water Table Depth
24. KBDI and NEXRAD Comparison
25. NEXRAD, KBDI, MWTD Comparison
26. KBDI MWTD NEXRAD
27. Data Spatial Resolution Temporal Resolution Real Time Temporal Sensitivity Variance Doppler Rainfall 4 km2 1 hour ~2 hour delay KBDI 4 km2 24 hours 24 hour delay MWTD 11 km2 Peninsular Florida only 24 hours 48 hour delay High Low High Low
28. Maintenance Amplification Early Transmission Late Transmission JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC IDD SWET SLE/WNV Arboviral Transmission Timeline IWET SDD Spatiotemporal Driving Forces Environmental Amplification Non-Epidemic Transmission Avian Reproduction Mosquito Egg Production Sentinel Transmission Human Transmission
29. Three Case Studies Dengue - Old Town, Key West, Florida - 2010 EEE – Volusia County, Florida – 2008/2009 West Nile Virus – Pinellas County, Florida - 2005
30. Dengue - Old Town, Key West, Florida - 2010
31. 0 10 20 30 40 50 60 70 80 90 100 Jan Jan Jan Jan Feb Feb Mar Mar Mar Apr Apr Apr May May May May June June June July July July Aug Aug Aug Sept Sept Sept Oct Oct Oct Nov Nov Nov Dec Dec Dec Temperature (F°) Daily Max Temp vs. Daily Max Average January through December, 2009 40 50 60 70 80 90 100 Jan Jan Jan Jan Feb Feb Mar Mar Mar Apr Apr Apr May May May May June June June July July July Aug Aug Aug Sept Sept Sept Oct Oct Oct Nov Nov Nov Dec Dec Dec Temperature (F°) Daily Max Temp vs. Daily Max Average January through December, 2010 30 40 50 60 70 80 90 100 110 Jan Jan Jan Jan Feb Feb Mar Mar Mar Apr Apr Apr May May May May June June June July July July Aug Aug Aug Sept Sept Sept Oct Oct Oct Nov Nov Nov Dec Dec Dec Temperature (F°) Daily Max Temp vs. Daily Max Average January through December, 2011
32. -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Inches Monthly Rainfall Deviation January through December, 2009 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Inches Monthly Rainfall Deviation January through December, 2010 -5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Inches Monthly Rainfall Deviation January through December, 2011
33. 0 1 2 3 4 5 6 Inches South Florida - Keys Daily Rainfall - Jan. thru Dec. 2009 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 Inches South Florida - Keys Daily Rainfall - Jan. thru Dec. 2010 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 Inches South Florida - Keys Daily Rainfall - Jan. thru Dec. 2011
34. 0 1 2 3 4 5 6 7 Inches Daily Epic Rainfall January through December, 2009 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 Inches Daily Epic Rainfall January through December, 2010 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 Inches Daily Epic Rainfall January through December, 2011
35. Dengue - Old Town, Key West, Florida
36. EEE – Volusia County, Florida – 2008 EEE positive equines through week 23 0f 2008 (n = 38)
37. EEE+ equines through week 23 (n = 38) Average EEE+ equines and Projected EEE+ equines Through June 2008 1. Where are we now?
38. 2. How did we arrive?
39. 3. Where are we now relative to past outbreaks?
40. 4. Where are we headed? 90
41. 4 Rainfall Events Currently in work on identifying KBDI patterns related to EEE transmission in north Florida. EEE – Volusia County, Florida – 2008
42. EEE Transmission in NE Florida Four wetting events Jan – Mar 2008 January 15th = 1 EEE+ Horse March 4th = 2 EEE+ Horses March 18th = 7 EEE+ Horses Date Associated Infections January 23rd = 6 EEE+ Horses EEE – Volusia County, Florida – 2008
43. EEE – Volusia County, Florida – 2009
44. EEE – Volusia County, Florida – 2008
45. Keetch-Byram Drought Index Week 20 May 15, 2009
46. Keetch-Byram Drought Index Week 21 May 22, 2009
47. Keetch-Byram Drought Index Week 24 June 17, 2009
48. 34 Equines 49.3 % EEE – Volusia County, Florida – 2009
49. June 30, 2009 Observed EEE – Volusia County, Florida – 2009
50. Oct 31, 2009 Observed EEE – Volusia County, Florida – 2008
52. West Nile Virus – Pinellas County, Florida - 2005
53. West Nile Virus – Pinellas County, Florida - 2005
54. West Nile Virus – Pinellas County, Florida - 2005
55. West Nile Virus – Pinellas County, Florida - 2005
56. West Nile Virus – Pinellas County, Florida - 2005
57. West Nile Virus – Pinellas County, Florida - 2005
58. What do we really know?
59. We need both real-time environmental data and long-term case data to understand arboviral transmission patterns in Florida.
60. It is still very complicated!!
61. Questions?