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Week 33 ending Aug 20, 2016
Dallas County Health and Human Services
Arbovirus Surveillance Report
†One mosquito trap containing only Aedes albopictus was positive for WNV, and is not included in VI calculations.
*Data for most recent 2 weeks are preliminary, and reflect results reported as of 10:30 a.m. August 22, 2015.
a. All traps deployed in municipalities submitting data to DCHHS since Week 13. Includes traps without mosquitoes, malfunctioning traps and traps with pending results
b. Excludes traps without female Culex quinquefasciatus identified. Maximum of 50 female Culex quinquefasciatus per pool; more than 1 pool may be tested per trap
c. PHL = Public health laboratory (DSHS, DCHHS) testing performed by viral culture or CDC RT-PCR protocol; IL = Testing from independent labs by alternate methods
d. Average abundance of female Culex quinquefasciatus mosquitoes per trap night/week (excludes non-working traps)
e. WNV Infection rates calculated using a Maximum Likelihood Estimation (MLE). Biggerstaff BJ. PooledInfRate, version 4.0; Microsoft Excel Add-In; CDC 2007
f. The Vector Index (VI) reflects the MLE adjusted for Culex quinquefasciatus abundance. VI= ∑ �̅�𝒊�̂�𝒊𝒊=𝒔𝒑𝒆𝒄𝒊𝒆𝒔 , where N is the average number of Culex quinquefasciatus
mosquitoes collected per trap night and �̂� is the estimated infection rate
g. Human cases by week of report to health department. WNND = West Nile Neuroinvasive Disease; WNF = West Nile Fever
h. All Biogents (BG) Sentinel traps deployed in municipalities submitting data to DCHHS since Week 15. Includes traps without mosquitoes, malfunctioning traps
i. Average abundance of Aedes albopictus and Aedes aegypti mosquitoes per night/trap in BG-Traps (excludes non-working traps)
j. Human CHKV cases by week of report to health department (AT : Autochthonous case; I : imported)
k. Human Dengue cases by week of report to the health department
l. Confirmed human Zika cases by week of report to health department (Excludes any pregnant cases)
m. Possible Zika Virus Infection Among Pregnant Women — United States and Territories, May 2016, http://www.cdc.gov/mmwr/volumes/65/wr/mm6520e1.htm/
Week Ending 7/9 7/16 7/23 7/30 8/6 8/13 8/20 YTD
MMWR Week 27 28 29 30 31 32* 33*
Total Traps Placed in Dallas County a 238 240 249 239 252 246 236 4,155
Number of Positive Mosquito Traps (PHL; IL) c 50†; 5 45; 4 41; 3 52; 3 51†; 5 29; 1 26; 2 428; 39
Number of Pools Tested (PHL; IL) b,c 218; 26 192; 31 209; 22 216; 30 214; 24 166; 23 140; 28 3,687; 437
Number of Trap Results Currently Pending 0 0 0 0 0 33 57
Average Number of Cx. quinquefasciatus per Trap d 29.9 17.6 23.3 31.0 21.2 18.4 20.1 35.1
Total Number of Cx. quinquefasciatus Trapped and Tested 5,954 3,853 4,617 6,191 4,763 3,716 3,589 109,007
Number of Positive Mosquito Pools (PHL; IL) c 50; 5 47; 4 43; 3 56; 3 53; 5 30; 1 26; 2 459; 39
WNV Infection Rate per 1,000 Cx. quinquefasciatus e 10.86 16.37 12.01 11.78 15.31 9.83 8.81
Weekly Vector Index (VI) f 0.32 0.29 0.28 0.36 0.32 0.18 0.18
Presumptive WNV Viremic Blood Donors 0 0 0 0 0 0 0 0
WNV Human Cases (WNND; WNF) g 1; 0 1; 0 1; 6 4; 1 3; 1 1; 0 4; 4 15; 12
Week Ending 7/9 7/16 7/23 7/30 8/6 8/13 8/20 YTD
MMWR Week 27 28 29 30 31 32* 33*
Total Biogents Sentinel-Traps Placed in Dallas County h 27 37 37 39 39 37 31 592
Average Number of Aedes per Trap i 7.1 7.8 5.1 5.0 5.7 5.9 3.0 5.6
Chikungunya Human Cases (Confirmed & Probable) j 0 1 0 0 0 0 0 2
Dengue Human Cases (Confirmed & Probable) k 0 0 0 1 1 0 0 2
Zika Human Cases (Confirmed Only) l 1 3 3 3 1 4 4 30
Pregnant Women with Possible Zika Infection m 1 0 1 0 0 0 2 14
In week 32, 30 mosquito traps tested positive for WNV. In week 33 to date, 28 mosquito traps have tested positive for WNV in zip codes: 75039, 75043, 75044, 75052, 75062, 75089, 75104, 75115, 75137, 75149, 75150, 75181, 75218, 75223, 75225, 75229, 75230, 75244, 75252, 75287.
Twenty seven human WNV cases, including 15 patients with neuroinvasive disease have been reported.
To date, 731 Dallas County residents have been tested for Zika infection.
Thirty travel-associated confirmed cases of Zika infection have been identified in Dallas. An additional 14 pregnant women with laboratory criteria for possible Zika infection have been reported to CDC for US Zika Pregnancy Registry surveillance, 3 of whom had symptoms.m
Aedes albopictus and Aedes aegypti continue to circulate in the area.
Table 1. Mosquito Laboratory and Human Case Surveillance Data for WNV, Dallas County
Table 2. Mosquito Laboratory and Human Case Surveillance Data for Chikungunya, Dengue and Zika Virus, Dallas County
PHONE EMAIL WEB
DCHHS Epidemiology (214) 819-2004 [email protected] www.dallascounty.org/hhs
*Data for most recent 2 weeks are preliminary
Week Ending 7/9 7/16 7/23 7/30 8/6 8/13 8/20 YTD
MMWR Week 27 28 29 30 31 32* 33*
# Human
WNV Cases Range Total # of Traps per Week1
# WNV+ Traps
# WNV+ Traps
# WNV+ Traps
# WNV+ Traps
# WNV+ Traps
# WNV+ Traps
# WNV+ Traps
Addison 1 2 1 1 0 1 1 0 Pending 7
Balch Springs 0 3 0 0 0 2 1 1 0 10
Carrollton 1 7 4 2 3 1 2 0 Pending 27
Cedar Hill 0 5 1 0 1 0 1 0 1 5
Cockrell Hill 0 1 0 0 0 1 0 0 0 2
Coppell 1 6 1 2 3 2 1 3 Pending 20
Dallas 17 68 - 85 12 8 10 11 13 6 9 100
DeSoto 1 6 3 2 0 2 4 1 3 17
Duncanville 0 5 1 0 2 1 1 2 1 10
Farmers Branch 0 4 1 2 0 2 1 0 Pending 9
Garland 0 20 - 27 5 2 3 6 7 0 3 30
Grand Prairie 0 24 - 30 4 4 3 3 4 0 2 33
Highland Park 0 2 - 6 1 2 0 2 0 0 0 6
Hutchins 0 1 1 0 1 1 0 1 0 4
Irving 4 13 - 15 5 6 6 4 6 4 4 57
Lancaster 0 4 0 1 1 1 1 2 0 7
Mesquite 2 17 - 19 12 9 7 10 7 4 4 77
Richardson 0 8 - 12 1 0 2 1 3 3 0 14
Rowlett 0 6 - 7 1 4 1 3 1 1 1 16
Sachse 0 3 0 1 1 1 1 2 0 7
Seagoville 0 2 0 0 0 0 0 0 0 1
Sunnyvale 0 2 0 1 0 0 0 0 0 2
University Park 0 2 - 4 1 1 0 0 0 0 0 4
Wilmer 0 1 0 1 0 0 1 0 0 2
Total 27 55 49 44 55 56 30 28 467
Figure 1: All WNV Negative and Positive Mosquito
Traps Collected During 2016: Weeks 13-33* (N=4,155)
*Data for most recent 2 weeks are preliminary, and reflect results reported as of 10:30 a.m. August 22, 2015. “Pending” indicates that no results for any traps have yet been
received. 1Range of numbers of traps placed weekly, in weeks 25-32.
Positive Traps Negative Traps Pending Traps
Table 3. WNV Positive Gravid Mosquito Traps by City, Dallas County*
Figure 2: Cumulative WNV Positive Mosquito Traps
Collected: Weeks 13-33* (N=467)
PHONE EMAIL WEB
DCHHS Epidemiology (214) 819-2004 [email protected] www.dallascounty.org/hhs
*Data for most recent 2 weeks are preliminary
** Vector Index of 0.50 is the historical threshold associated with larger local epidemics of WNV illnesses in humans. Note: Most recent 1-2 weeks data are preliminary and subject to change following receipt of data still pending.
< 100 Mosquitoes/Trap 100 - 499 Mosquitoes/Trap
500 - 1000 Mosquitoes/Trap >1000 Mosquitoes/Trap
Positive Traps
Figure 4: Trap Counts of Female Cx. quinquefasciatus
from 2016 Season: Weeks 13-33*
Figure 3: WNV Positive Mosquito Traps Collected During
2016: Weeks 32 and 33* (N=58)
Figure 5: Average Numbers of Female Cx. quinquefasciatus per Trap-night and WNV Vector Index by Week:
2012 Season and 2016 Season (through Week 33*)
0.0
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14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
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Collection Date by MMWR Week
Average Abundance 2016
Average Abundance 2012
2016 VI
2012 VI
**
*Figure 4 only shows traps for which results were available; malfunctioning traps were excluded. Almost all traps are at fixed sites. Note: Most recent 1-2 weeks data are preliminary and subject to change following receipt of data still pending.
PHONE EMAIL WEB
DCHHS Epidemiology (214) 819-2004 [email protected] www.dallascounty.org/hhs
0.0
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1 14 27 41 1 14 27 41 1 14 27 41 1 14 27 41 1 14 27
2012 2013 2014 2015 2016
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MMWR Week - Year
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1 14 27 41 1 14 27 41 1 14 27 41 1 14 27 41 1 14 27
2012 2013 2014 2015 2016
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MMWR Week - Year
Figure 6: WNV Vector Index by Week: 2012 - 2016 Seasons
Figure 7: Average Numbers of Female Cx. quinquefasciatus per Trap-night by Week: 2012 - 2016 Seasons
The Vector Index (VI) reflects the MLE adjusted for Culex
quinquefasciatus abundance. VI= ∑ 𝑁𝑖�̂�𝑖𝑖=𝑠𝑝𝑒𝑐𝑖𝑒𝑠 , where N
is the average number of Culex quinquefasciatus mosquitoes
collected per trap night and �̂� is the estimated infection rate
PHONE EMAIL WEB
DCHHS Epidemiology (214) 819-2004 [email protected] www.dallascounty.org/hhs
0.00
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18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
5/5 5/12 5/19 5/26 6/2 6/9 6/16 6/23 6/30 7/7 7/14 7/21 7/28 8/4 8/11 8/18 8/25 9/1 9/8 9/15 9/22 9/29 10/6 10/13 10/20 10/27 11/3 11/10 11/17 11/24 12/1 12/8
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MMWR Week - Week Ending
Human WNV Cases
Viremic Blood Donors by Date of Report
Vector Index
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1 14 27 41 1 14 27 41 1 14 27 41 1 14 27 41 1 14 27
2012 2013 2014 2015 2016
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MMWR Week - Year
Figure 9: WNV Vector Index, Viremic Blood Donors, and Human WNV Cases by Week of Report:
2012 Season
*
Figure 8: MLE (WNV Infection Rate per 1,000 Cx. quinquefasciatus) by Week: 2012 - 2016 Seasons
PHONE EMAIL WEB
DCHHS Epidemiology (214) 819-2004 [email protected] www.dallascounty.org/hhs
Country/Territories # Human Zika Cases (%)
Mexico 7 (23.3)
Jamaica 4 (13.3)
Guatemala 4 (13.3)
Honduras 3 (10.0)
Dominican Republic 2 (6.7)
El Salvodor 2 (6.7)
Puerto Rico 2 (6.7)
Belize 1 (3.3)
Virgin Islands 1 (3.3)
Colombia 1 (3.3)
Venezuela 1 (3.3)
Nicaragua 1 (3.3)
Trinidad 1 (3.3)
Total 30
Figure 12: Average Numbers of Aedes albopictus per Trap-night:
2015 and 2016 Seasons*
Figure 10: BG-Sentinel Trap Counts of Female Aedes aegypti and Aedes albopictus During 2016: Weeks 15 through 33
* 0
5
10
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45
15 17 19 21 23 25 27 29 31 33 35 37 39 41
Ave
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alb
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Collection Date by MMWR Week
2016
2015
June Aug OctApril
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15 17 19 21 23 25 27 29 31 33 35 37 39 41
Ave
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edes
aeg
ypti
Collection Date by MMWR Week
2016
2015
June Aug OctApril
0 Mosquitoes/Trap <10 Mosquitoes/Trap
10-30 Mosquitoes/Trap >30 Mosquitoes/Trap
Figure 11: Average Numbers of Aedes aegypti per Trap-night:
2015 and 2016 Seasons*
*Aedes BG-Sentinel trapping began Week 22 in 2015
Table 4: Travel-Associated Zika Infections by Country/Territories: 2016 Season, Dallas County
PHONE EMAIL WEB
DCHHS Epidemiology (214) 819-2004 [email protected] www.dallascounty.org/hhs
0
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Figure 13: Syndromic Surveillance of Emergency Department Visits for Chief Complaints of Rash, Dallas County:
January 1, 2016 – August 20, 2016
,
Data source: 18 emergency departments in Dallas County hospitals participating in the Electronic Surveillance System for the Early Notification Of Community-based Epidemics (ESSENCE) voluntarily reporting the numbers of persons presenting with self-reported chief complaints of rash.
Data alert Data warning Data normal