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Vibrio vulnificus Calculator

Vibrio vulnificus Calculator. VMC/Gulf Regulators Conference Call August 1, 2008. ISSC adopted Vv illness reduction plan–1999?. 60% illness reduction goal (per capita) Core states: CA, TX, LA & FL Baseline 1995-1999: 21.4 cases/yr Education and increasing PHP capacity

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Vibrio vulnificus Calculator

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  1. Vibrio vulnificus Calculator VMC/Gulf Regulators Conference Call August 1, 2008

  2. ISSC adopted Vv illness reduction plan–1999? • 60% illness reduction goal (per capita) • Core states: CA, TX, LA & FL • Baseline 1995-1999: 21.4 cases/yr • Education and increasing PHP capacity • 7 year plan with reductions based on ave # cases in 2007 & 2008

  3. Current Status • 2007 cases=19 • 24.8% reduction from baseline • Adjusted for population increase • 2008 partial cases=3 • Plan does not reach goal if 20 or more cases occur in 2007 & 2008 combined • Goal will not be met • Goal shortfall cannot be determined until after 2008

  4. Consequences of not achieving goal • Seasonal closures (100% effective) • Diversion to PHP (100% effective) • Label “for cooking only” OK for Vv? (100% effective) • Other means? • Time/temperature controls • High salinity relaying • ISSC Spring Executive Board Mtg • Gulf States submit control plan by Aug. 15, 2008 (amended?) • States implement plans in 2010

  5. Time/Temperature Controls • GSASSC New Orleans June 2008 • Gulf regulators requested that FDA develop risk calculator similar to that proposed for VPCP • Vv Risk calculator • Based on 2005 FAO/WHO VVRA • Dose response based on reported cases in US

  6. Beta Poisson vs Exponential

  7. Vv Calculator Features • Derived from FAO/WHO VVRA • Monte Carlo simulations • Time consuming • Expensive software • Trained operators • Vv risk calculator • Based on regression fits to a set of Monte Carlo simulation output • Calculates Vv levels & risk instantly • Flexible to evaluate diverse scenarios and different end points for desired level of illness reduction

  8. Average monthly maximum water temperature (AMMWT) • Determines Vv levels at harvest based on relationship between water temperature & Vv level from Vv risk assessment (VVRA) • State determines scale: area, basin or entire state (buoy, sampling) • Gulf-wide

  9. Effect of Temperature on Vv densities in Gulf Coast oysters

  10. Average monthly air temperature • Surrogate for oyster temperature • Determines Vv growth rate • Ave. air temperature determination • Ave. monthly noon air temperature • Ave. monthly maximum temperature • Ave. monthly air temperature during harvest period (i.e. 6-11 AM) • Ave. oyster temperature during harvest period

  11. Baseline: max. time to refrigeration • Controls that were in place during the baseline period of 1995-99 • Vary from state to state • Alternatively 10h for summer month? • Represents control used for most Gulf oyster harvest

  12. Baseline: Max cool down time • Time from when oysters are first placed into refrigeration until reach no growth temperature of 13C or 55F • 10 hour is assumption used in both FDA VPRA and FAO/WHO VVRA • Ave cool down between 1 to 10 hours

  13. Demonstration of using Vv risk calculator • Baseline (1995-99) controls • Effect of VPCP on Vv risk • Risk at harvest (best case scenario)

  14. Calculator Inputs • Average monthly water temperature • Average monthly air temperature • Maximum time to first refrigeration • Maximum cool down time

  15. Calculator Outputs • Vv levels at consumption • Vv risk per 100,000 meals • Number of cases per month (Nation wide) • % change in number of cases from the baseline

  16. Baseline Demonstration Open Excel Vv Calculator Tab

  17. Effect of VPCP on Vv Risk <5h if >81F Tab

  18. Vv Risk at Harvest Risk at Harvest Tab

  19. Caveats • Dose response not linear & does not provide outputs above 90F and >15h to first refrigeration • Controls changed in 1997 during baseline period (1995-99) • Controls vary across Gulf states • Implementation of VPCP in 2008 • Max. time to refrigeration • Changes in volume of harvest for raw consumption? • % raw consumption varies across Gulf states

  20. Summary • Scenario analysis • Manage on monthly scale • Modify time to refrigeration and cool down times • Outputs • Vv levels at consumption • Vv risk per 100,000 meals (at risk population) • Expected number of cases • Change from baseline

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