1. Diana Cervantes, MS, MPH Epidemiologist Tarrant County Public Health

2. Tarrant County: ~ 1.8 million citizens Ecology Culture
Forrest to grassland prairies
Urban to rural
Culture
Very little history of mosquito spraying
WNV response began in 2002
Mosquito surveillance/testing (2003)
Focus on surveillance and prevention
awareness and education
Open grassland, not as much shade compared to forest
Culex quin urban high density
TC no history of spraying, 5 cities that routinely spray prior to and then increased to 8-9 (2 cities areal spraying Haslet and S. lake in Denton partially)

3. Historical WNV Human Case Data Tarrant County, 2002-2011
WNV associated mortality: 1 in 2002; 7 in 2006; 3 in 2009

4. 2012 Human case counts in Tarrant County*
Total cases: 279
WNF -178
WNND
Deaths - 11
Incidence rate per 100,000: 14.5
Cities with cases - 24
24 with cases
Part or all (GP some in Dallas Co) of 41 cities in TC and there are unincorporated areas in TC we cover
*For 2012 Arboviral season; Based on data reported as of 5:00 PM 02/22/2013

5. WNV Cases by Onset of Illness, Tarrant County, 2012
Average time from when a person became ill until the case was reported to TCPH was 17.7 days.
Data source: Tarrant County Public Health

6. Use of Insect Repellent While Outdoors among Tarrant County WNV Cases, 2012*
*Regardless of time spent outdoors; 2012 Arboviral season; Based on data from Tarrant County cases reported as of 11:00 AM February 21, 2013

7. Tarrant County Response
Mosquito surveillance
Resurgence of interest in participation
TCPH LRN operated to capacity
Adulticide application
Varied among municipalities
No generalized aerial spraying
Targeted ground spraying effective
IR was average among the metroplex counties…not the highest or the lowest
Risk communication
32 mosquito surveillance participants down to 26 (fort worth and Arlington dropped out) but now participating again
Prior to 2012, 5-6 cities spraying and then jumped to 8-9
Aerial spraying
* Enhanced communication within TC and with 41 cities

8. Lessons learned
Limitations of using human case data to drive control efforts
Limitations of mosquito surveillance data
program implementation
No standard/structured trapping
No historical trap data
Effective communication is critical
Stakeholders
Media
Public
Local/regional partners
Due to the culture in TC of now spraying, human cases drove the response in municipalities (mosquito collections, spraying). There is a need to focus on the front end and CONTROL of mosquito populations to prevent cases in addition to prevention due to the four D’s (Dusk/Dawn, drain, dress, DEET)
Traps, no fixed locations: general numbers but traps mobile
As with any surveillance program need to have a continuous loop of data collection, analysis, interpretation, dissemination

9. West Nile Neuroinvasive Disease CSTE Epidemiologic Case Definition
Must meet Laboratory Criteria AND Clinical Criteria
Clinical Criteria:
Fever, (>100.4 or 38C) as reported by pt or HCP, AND
Meningitis, encephalitis, acute flaccid paralysis, or other acute signs of central or peripheral neurologic dysfunction, as documented by a physician, AND
Absence of a more likely clinical explanation
NOTE: there is a great deal of variability (no standard) in determination of WNV fever versus WNND. In the case investigation form, are other agencies basing information ONLY as documented by a physician or also based on case reported signs/symptoms? What signs/symptoms or combination of signs/symptoms is DSHS using to

10. Recommendations for future response
Review/revise
response plans to increase mosquito pool surveillance
operational plans to reflect surveillance data (mosquito data to drive response)
communication plans
Communications with those in the position to make decisions
Increase number of traps and in fixed locations
so that data can be used to inform control efforts.
Communication to appropriate parties that can instigate response/change

11. Acknowledgements Tarrant County TX DSHS
Environmental Health
Epidemiology and Health Information
TX DSHS
Central
Region 2/3
North Texas local public health