2008 - 2009 Texas Influenza Surveillance Information
Influenza Surveillance Report for MMWR Week 4
The influenza (flu) activity level for Texas for the week ending January 31, 2009 was “widespread.” Widespread activity indicates that at least half of the regions in the state are experiencing an increase in influenza-like illness (ILI) and have recent culture-confirmed influenza. During week 4, 474 (31.3%) specimens tested by NREVSS laboratories in Texas were positive for influenza. The percentage of visits for influenza-like illness as reported by ILINet providers in Texas exceeded the regional baseline.
Reports from Health Service Regions
Reports were received from all Health Service Regions (HSRs) for week 4. HSRs 8, 9/10, and 11 reported the same level of flu activity compared to week 3. All other HSRs reported an increase in flu activity compared to week 3. For a map of Health Service Regions, please visit the following website:
http://www.dshs.state.tx.us/regions/state.shtm
Laboratory Results
During week 4, seven hospital laboratories and public health agencies across Texas reported conducting a total of 1,514 influenza tests (antigen, culture, and PCR) to the National Respiratory and Enteric Virus Surveillance System (NREVSS ) sponsored by the Centers for Disease Control and Prevention (CDC). Of the 1,345 antigen detection tests that were performed, 328 were positive for influenza A/not subtyped and 77 were positive for influenza B. The positive results were reported from Bell, Bexar, Collin, Lubbock, and Tarrant counties. Twenty-nine PCR tests positive for influenza A/H1, twenty-six PCR tests positive for influenza A/not subtyped, and forty-one PCR tests positive for influenza B were reported for Bell, Harris, Lee, Tarrant, and Williamson counties. [There may be some overlap in the PCR and culture positive results described in this report (i.e., some of the PCR results may be from some of the same patients as the culture results).] A total of 364 reports of culture-confirmed influenza were received from public health laboratories in Austin, Dallas, and Houston; Scott & White Memorial Hospital in Temple; Texas Children's Hospital in Houston; and other sources for the following counties:
| Influenza A/H1 |
Influenza A/H3 |
Influenza A/not subtyped |
Influenza B |
| Anderson County |
Dallas County (2) |
Bell County (9) |
Angelina County |
| Angelina County (3) |
Tarrant County |
Bexar County (46) |
Bell County (9) |
| Dallas County |
|
Brazos County (12) |
Bexar County (2) |
| Kleberg County (2) |
|
Burleson County |
Brazos County (12) |
| Travis County (13) |
|
Dallas County (105) |
Brooks County |
| |
|
Falls County |
Dallas County (24) |
| |
|
Harris County (37) |
Harris County (52) |
| |
|
Hill County |
Leon County |
| |
|
McLennan County (11) |
McLennan County (5) |
| |
|
Williamson County (8) |
Travis County (3) |
Additional positive results from point-of-care rapid flu tests were reported by providers throughout the state (see Texas map below).
Antigenic Characterization
CDC has reported antigenic characterization results from 26 influenza isolates [14 influenza A/H1, 1 influenza A/H3, and 11 influenza B viruses] received from the DSHS Laboratory since the beginning of the 2008–09 flu season.
Influenza A/H1 [14]
- All 14 viruses were characterized as A/Brisbane/59/2007, the influenza A/H1 component of the 2008–09 influenza vaccine for the Northern Hemisphere.
Influenza A/H3 [1]
- One virus was characterized as A/Brisbane/10/2007, the influenza A/H3 component of the 2008-09 influenza vaccine for the Northern Hemisphere.
Influenza B (B/Victoria/02/87 and B/Yamagata/16/88 lineages) [11]
Victoria lineage [10] - Two (20%) of the ten viruses were characterized as B/Ohio/01/2005-like viruses.
- Eight (80%) of the ten viruses showed somewhat reduced titers with antisera produced against B/Malaysia/2506/2004 and B/Ohio/01/2005.
Yamagata lineage [1]
- One virus was characterized as B/Florida/4/2006, the influenza B component for the 2008-09 influenza vaccine.
Antiviral Resistance
Since September 28, 2008, 12 influenza A/H1 isolates and 11 influenza B isolates from the DSHS laboratory have been tested by CDC for antiviral resistance.
| |
Isolates Tested (n) |
Resistant Viruses,
Number (%)
|
Isolates Tested (n) |
Resistant Viruses,
Number (%)
|
| Oseltamivir |
Zanamivir |
Adamantanes |
| Influenza A/H1 |
12 |
11 (92%) |
0 (0) |
12 |
0 (0) |
| Influenza A/H3 |
0 |
N/A |
N/A |
0 |
N/A |
| Influenza B |
11 |
0 (0) |
0 (0) |
N/A* |
N/A* |
*Adamantanes are not effective against influenza B viruses. CDC has issued interim recommendations for use of antiviral medications in the 2008-09 influenza season. Those recommendations are available at: http://www.cdc.gov/flu/professionals/antivirals/index.htm..
Influenza–Associated Pediatric Mortality
No influenza-associated pediatric fatalities occurred during week 4. Texas has reported one influenza-associated pediatric fatality during the 2008-09 influenza season.
School Closures and Institutional Outbreaks
School closures and institutional outbreaks due to influenza and influenza-like illnesses were reported in multiple schools during week 4. The same school in Henderson County that reported several rapid tests positive for influenza B during week 3 continued to report a large number of influenza cases during week 4. Two schools in Angelina County reported large numbers of influenza cases. One school in Wood County closed during week 4 due to influenza-like illnesses. One boarding school in Bexar County closed due to influenza.
U.S. Outpatient Influenza-like Illness Surveillance Network
Fifty-nine sentinel providers in Texas reported data to the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) (formerly known as the U.S. Influenza Sentinel Provider Surveillance System) on patients with influenza–like illness (ILI) and total patients seen for any reason during week 4. Forty-five (76%) of these providers saw at least one patient with ILI. Of all patient visits during this week, 5.73% were due to ILI. The ILI baseline for the West South Central Region (Arkansas, Louisiana, Oklahoma, and Texas) of the United States is 4.8% for the 2008-2009 season. The baseline is the mean percentage of patient visits for ILI during non-influenza weeks for the previous three seasons plus two standard deviations.
| Percentage of Visits for Influenza–Like Illness Reported by the US Outpatient Influenza–Like Illness Surveillance Network (ILINet) in Texas as of 2/6/2009 10:52:27 AM |
| Week |
# Reporting |
Age 0-4 |
Age 5-24 |
Age 25-64 |
Age over 64 |
Total ILI |
Total Patients |
% ILI |
| 2008-40 |
77 |
84 |
133 |
127 |
22 |
366 |
20231 |
1.81 |
| 2008-41 |
77 |
114 |
163 |
124 |
19 |
420 |
20000 |
2.10 |
| 2008-42 |
78 |
107 |
156 |
90 |
7 |
360 |
19658 |
1.83 |
| 2008-43 |
78 |
120 |
152 |
106 |
20 |
398 |
19654 |
2.03 |
| 2008-44 |
79 |
136 |
199 |
103 |
26 |
464 |
20653 |
2.25 |
| 2008-45 |
77 |
110 |
111 |
122 |
27 |
370 |
20737 |
1.78 |
| 2008-46 |
72 |
110 |
106 |
103 |
23 |
342 |
19684 |
1.74 |
| 2008-47 |
74 |
137 |
143 |
122 |
19 |
421 |
19722 |
2.13 |
| 2008-48 |
78 |
131 |
132 |
125 |
37 |
425 |
16835 |
2.52 |
| 2008-49 |
76 |
143 |
159 |
153 |
24 |
479 |
20226 |
2.37 |
| 2008-50 |
74 |
133 |
146 |
108 |
28 |
415 |
19221 |
2.16 |
| 2008-51 |
68 |
172 |
177 |
175 |
24 |
548 |
17438 |
3.14 |
| 2008-52 |
75 |
194 |
153 |
154 |
34 |
535 |
13360 |
4.00 |
| 2008-53 |
75 |
167 |
137 |
165 |
46 |
515 |
14933 |
3.45 |
| 2009-01 |
77 |
162 |
182 |
188 |
38 |
570 |
18423 |
3.09 |
| 2009-02 |
74 |
177 |
287 |
230 |
41 |
735 |
19587 |
3.75 |
| 2009-03 |
73 |
167 |
446 |
336 |
40 |
989 |
21876 |
4.52 |
| 2009-04 |
59 |
240 |
620 |
305 |
35 |
1200 |
20944 |
5.73 |
National Influenza Activity Map
The map showing influenza activity in the United States for MMWR week 4 is displayed below. The current U.S. flu weekly report may be found at: here.
 *This map indicates geographic spread and does not measure the severity of influenza activity.
For more information on flu surveillance activities in the State of Texas, please visit our main surveillance page.
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