1. EEE Decision Making
July 26, 2012

2. Timeline of Events First EEE mosquitoes, mammal-biting, Carver
Meeting to discuss data and possible responses, including aerial spray
EEE positives from Rehoboth, bird and mammal-biter
First EEE mosquitoes, bird and mammal-biting, Easton, Raynham and Taunton moved to high risk
Additional positives from Easton and Lakeville
First EEE mosquitoes, bird-biting, Lakeville
Aerial spray
July 11
July 12
July 13
July 16
July 17
July 18
July 20-22
Decision to aerial spray made
Additional trapping and testing throughout area

3. Comparison of First EEE Result Dates by Year

4. Historic Indicators applicability to 2012
Above average rainfall in prior fall and spring NO
Mild winter with insulating snow cover YES
EEE activity in the previous year YES
Isolation of EEE virus from a mammal-biting mosquito species YES
Infection of a human prior to late August NO
Higher than average summer temperatures YES

5. C. melanura Mosquito Populations
C. melanura (bird-biting mosquito) is about average right now in Peaks in the population have been associated with occurrence of human infections was an example of this.

6. EEE Infection Rate in C. melanura
MIR provides a measure of the proportion of infected mosquitoes in the population. Peaks in MIR have been associated with occurrence of human infections.

7. AIF Comparison
Multiplying mosquito population numbers by the infection rate creates a new risk indicator called the Abundance Infection Factor, AIF, which provides a measure of the density of the infected mosquito population. The Expert Panel recommended evaluation of this as a new tool for risk assessment.

8. Criteria for Inclusion in Spray
Current EEE isolations
Known breeding habitat
Areas of historic risk

9. Bristol County Activity
Proportion of C. perturbans (mammal-biting) infected in Bristol County traps only, comparison with 2010 and 2011
MIR in week 29 = 13.1

10. Approximate Locations of Positive Mosquito Traps with ~5 mile radius for Initial Discussion Purposes ONLY 10

11. Comparison of current activity zone (red) and 2006 and 2010 spray zones
2012
2010
2006b
2006a

12. Recent EEE Virus Activity in Plymouth and Bristol Counties: 2004-2012
Color codes: Gray indicates human or horse case
Yellow indicates EEEv(+) mammal biting mosquitoes

15. Final Area Spray Zone Map Including Areas of Historic Risk

16. Public Risk Communication
Areas at High Risk have all reported cooperating with advice to reschedule evening, outdoor events
MCPs are continuing ground-spraying
Personal prevention messages being stressed in releases