Tarrant County Influenza Surveillance Weekly Report CDC ...

Tarrant County Public Health Division of Epidemiology and Health Information

Tarrant County Influenza Surveillance Weekly Report CDC Week 40: Sept 29-Oct 5, 2019

Influenza Activity Code: County and State Levels

Tarrant County: Week 40

Sporadic

Tarrant County: Week 39

Sporadic

Texas: Week 39

Not Determined

Respiratory Virus Activity Summary

? The percentage of reported influenza-like illness (ILI) in Tarrant County increased from 1.4%

in week 39 to 1.7% in week 40 and is currently below the 2019-2020 Tarrant County baseline (2.4%).

? The percentage of all cause school absenteeism was 3.2% during week 40 in Tarrant County.

Absenteeism due to ILI and school nurse office visits due to ILI were 1.7% and 1.1% respectively during week 40 in Tarrant County.

? The percentage of rapid flu test positives in Tarrant County decreased from 2.9% in week 39

to 2.2% in week 40.

? During the 2019-2020 influenza season, 0 Tarrant County influenza-associated pediatric

deaths have been reported. As of week 39, 17 influenza-associated pediatric deaths have been reported in Texas, with a total of 136 reported nationwide for the 2017-2018 season.

? During the 2019-2020 influenza season, 0 influenza outbreaks have been reported in Tarrant

County schools and 0 localized influenza outbreak has been reported within institutions in Tarrant County.

? Since last report, 8 surveillance specimens were tested by The North Texas Regional

Laboratory. The following types and number of viruses were detected in these specimens: Rhinovirus (3) and Adenovirus (1). Cumulatively this season, the North Texas Regional Laboratory at Tarrant County Public Health has tested 8 surveillance specimens and of these, 0 have been positive for influenza.

? In Texas during week 39, the proportion of outpatient visits for ILI, 2.1%, was below the state

baseline of 5.6%.

? Nationally during week 39, 3.4% of specimens tested and reported to the CDC were positive

for influenza. The proportion of outpatient visits for ILI (1.3%) was below the national baseline (2.2%). The proportion of deaths in week 37 attributed to pneumonia and influenza from the National Center for Health Statistics (5.0%) was below the epidemic threshold (5.7%).

% ILI

Influenza Like Illness (ILI): Local and State Levels

15.0% 14.0% 13.0% 12.0% 11.0% 10.0%

9.0% 8.0% 7.0% 6.0% 5.0% 4.0% 3.0% 2.0% 1.0% 0.0%

Graph 2. Texas and Tarrant County % ILI

Tarrant County % ILI Texas % ILI

Texas Baseline Tarrant County Baseline

33 35 37 39 41 43 45 47 49 51 01 03 05 07 09 11 13 15 17 19 21 23 25 27 29 31 33

Aug Sept Oct

Nov Dec

Jan

Feb March April May June July

Aug

CDC Week

100.0% 80.0% 60.0% 40.0%

5.6% 34.3%

26.9%

Graph 3. ILI % by Age Groups, Tarrant County

4.1%

5.0%

4.9%

4.8%

2.5%

4.4%

3.9%

36.1%

25.5%

29.1%

31.6%

27.8%

36.9%

32.9%

29.5%

39.5%

30.2%

32.7%

38.0%

27.4%

32.4%

ILI %

20.0%

33.3%

30.3%

30.0%

35.8%

31.0%

31.6%

31.2%

30.8%

0.0%

33

34

35

36

37

38

39

40

CDC Week

Age 0-4

Age 5-24

Age 25-64

Age >65

In week 40, 1.7% of visits to health care providers were due to ILI. ILI levels are currently below the county established baseline of 2.4% and are lower than the state of Texas levels from the week prior. In Tarrant County, of the 380 reported patients presenting with ILI during week 40, the age groups with the largest percentage of the reported ILI patients, 32.9% and 32.4%, were the 25-64 and 5-24 age groups, respectively.

NOTE: Tarrant County ILI activity is assessed using information provided by surveillance participants and the Electronic Surveillance System for the Early Notification of Community-based Epidemics (ESSENCE). For week 40, 21 surveillance participants - 17 Hospitals, 2 Colleges/Universities, 1 Emergency/Urgent Care Center, and 1 Business - reported ILI information to Tarrant County Public Health. Texas ILI activity is assessed using information provided by a network of providers . For week 39, 92 providers reported information to the Texas Department of State Health Services.

2

% ILI

40 41 42 43 44 45 46 47 48 49 50 51 52 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20

Tarrant County Historical ILI and ESSENCE Geographical Distribution Map

Graph 4. Tarrant County % of patient visits due to ILI during

flu season 2016-2017 through 2019-2020

14.0%

13.0%

2016-2017 Season

12.0% 11.0% 10.0%

2017-2018 Season 2018-2019 Season

9.0%

2019-2020 Season

8.0%

7.0%

6.0%

5.0%

4.0%

3.0% 2.0%

Tarrant County Baseline

1.0%

0.0%

Oct

Nov

Dec

Jan

Feb

March April

May

CDC Week

Map 1. Tarrant County ER ILI Cases by Zip Code, Week 40

Zip codes with 5 cases are assigned 0. Tarrant County ILI data by zip code is obtained from ESSENCE and includes ILI numbers from 46 hospitals that voluntarily provide data based on chief complaints of Tarrant County residents admitted to Emergency Departments in North Central Texas. Zip code population data is obtained from American Community Survey 2017 5 year estimate.

3

4.0%

Rapid Influenza Test Results and School Absenteeism

Graph 5. Absenteeism and ILI, Tarrant County

3.0%

2.0%

1.0%

0.0%

40

41

42

Average Daily % Absent Average Daily % ILI School Nurse Visits

43

44

45

46

CDC Week

Average Daily % Absent due to ILI

For week 40, 9 school districts provided general absenteeism data, 8 school districts provided data regarding absenteeism due to ILI, and 8 school districts provided data regarding nurses' office visits due to ILI.

Table 1. Influenza Rapid Test Results, Tarrant County

CDC Week Number

38 (Sept 15-21)

39 (Sept 22-28)

40 (Sept 29-Oct 5)

# Influenza Tests Performed

635

820

850

% Influenza Positive

2.8%

2.9%

2.2%

# Influenza A Positive

4

4

4

% Influenza A Positive

22.2%

16.7%

21.1%

# Influenza B Positive

14

20

15

% Influenza B Positive

77.8%

83.3$

78.9%

# Non-differentiated Positive

0

0

0

% Non-differentiated Positive

0.0%

0.0%

0.0%

NOTE: Tarrant County rapid influenza test results are reported weekly by influenza surveillance participants. For CDC week 40, rapid influenza test results were reported by 14 hospitals, 1 Emergency/Urgent Care Center and 2 colleges/ universities.

4

Influenza Confirmatory Test Results: Tarrant County

Table 2. North Texas Regional Laboratory: Respiratory Virus Results1

Number of Specimens Tested Positive Specimens

Current Week 8

4 (50.0%)

2019-2020 Season 8

4 (50.0%)

Influenza A Influenza B

0 (0.0%) 0 (0.0%)

0 (0.0%) 0 (0.0%)

Respiratory Syncytial Virus

0 (0.0%)

0 (0.0%)

Adenovirus

1 (25.0%)

1 (25.0%)

Human Metapneumovirus

0 (0.0%)

0 (0.0%)

Parainfluenza-1

0 (0.0%)

0 (0.0%)

Parainfluenza-2

0 (0.0%)

0 (0.0%)

Parainfluenza-3

0 (0.0%)

0 (0.0%)

Rhinovirus

3 (75.0%)

Inconclusive2

0 (0.0%)

1 Laboratory results based on real-time PCR analysis; information is -for the 2019-2020 season. 2 Inconclusive for influenza A and influenza B; not included in positive specimens count.

NOTE: Percentages do not add up to 100% due to co-infections

3 (75.0%) 0 (0.0%)

Table 3. North Texas Regional Laboratory: Influenza Results1

Current Week

2019-2020 Season

Influenza A

0

0

Influenza A H1

-

-

Influenza A H3

-

-

Influenza A, Inconclusive subtype

-

-

Influenza A, Unsubtypeable2

-

-

Influenza B

0

0

Influenza B Yamagata3

-

-

Influenza B Victoria3

-

-

Influenza B, Inconclusive

-

-

1 Laboratory results based on real-time PCR analysis; information is for the 2019-2020 season. 2 Influenza A subtype not determined; further analysis pending 3 Influenza B genotyping is only included in current week column if genotyping occurred in the same week as original PCR testing.

Graph 6. North Texas Regional Laboratory: Influenza Virus Results1

1

Influenza A H1

Influenza A H3

Influenza A, Inconclusive s ubtype Infl uenza B

Percent Pos itive

0 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

Oct Nov

Dec

Jan

Feb March April May June July

Aug Sept

CDC Week

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

5

Number of Positive Influenza Specimens

% of Positive Influenza Specimens

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