2008 - 2009 Texas Influenza Surveillance Information
Influenza Surveillance Report for MMWR Week 16
The influenza (flu) activity level for Texas for the week ending April 25, 2009 was “local.” During week 16, no 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 was below the regional baseline.
Reports from Health Service Regions
Reports were received from all Health Service Regions (HSRs) for week 16; however, due to the current swine influenza A/H1N1 investigations, regular reports from many sentinel providers were not received by the HSRs. HSR 4/5N reported an increased level of flu activity compared to week 15. HSRs 6/5S and 8 reported the same level of flu activity compared to week 15. All other HSRs reported a decreased level of flu activity compared to week 15. 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 16, five hospital laboratories and public health agencies across Texas reported conducting a total of 138 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). No tests were positive for influenza. A total of 12 reports of PCR- or culture-confirmed influenza were received from public health laboratories and the United States Air Force School of Aerospace Medicine (USAFSAM) for the following counties during week 16 (April 19-April 25):
Influenza A/H1 (seasonal) |
Influenza A/H3 |
Influenza A/not subtyped |
Influenza B |
Bexar County (2) |
(none) |
(none) |
Bexar County (3) |
Travis County |
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Wichita County (5) |
Wichita County |
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Positive point-of-care rapid tests for influenza were reported by providers throughout the state (see county map below).
Novel Influenza A Virus Infections (information updated 5/15/09)
A total of 52 cases of influenza A/H1 swine confirmed by the CDC have been reported with a known onset in week 16 (April 19-April 25) for the following counties (listed by patient county of residence):
Influenza A/H1 swine |
Bexar County (5) |
Cameron County |
Comal County (2) |
Dallas County (4) |
Denton County |
Fort Bend County (2) |
Guadalupe County (10) |
Harris County (3) |
Hidalgo County |
Jefferson County |
Johnson County |
Kendall County |
Montgomery County |
Starr County (5) |
Tarrant County (11) |
Taylor County |
Travis County |
Upshur County |
Additional specimens have been identified by PCR testing as positive for unsubtypeable influenza A; these specimens are being forwarded to CDC for further study. This information is subject to change as more reports are received. Thorough case and contact investigations are ongoing, and the number of confirmed cases changes frequently. Please see the DSHS website (http://www.dshs.state.tx.us/swineflu/default.shtm) and the CDC website (http://www.cdc.gov/flu/swine/) for more information on the current investigation.
Antigenic Characterization
CDC has reported antigenic characterization results from 48 influenza isolates [20 influenza A/H1, 6 influenza A/H3, and 22 influenza B viruses] received from the DSHS Laboratory since the beginning of the 2008–09 flu season. Influenza A/H1 [20]
- All 20 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 [6]
- All 6 viruses were 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) [22]
Victoria lineage [15] - Fifteen of the influenza B viruses were characterized as belonging to the B/Victoria lineage.
Yamagata lineage [7]
- Seven viruses were characterized as B/Florida/4/2006, the influenza B component for the 2008-09 influenza vaccine for the Northern Hemisphere.
Antiviral Resistance
Since September 28, 2008, 21 seasonal influenza A/H1 isolates, 6 influenza A/H3 isolates, and 21 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 |
21 |
21 (100%) |
0 (0) |
21 |
0 (0) |
Influenza A/H3 |
6 |
0 (0) |
0 (0) |
6 |
6 (100%) |
Influenza B |
21 |
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 in Texas residents were reported during week 16. Texas has reported ten influenza-associated pediatric fatalities during the 2008-09 influenza season.
School Closures and Institutional Outbreaks
School closures were reported in HSR 8 (Guadalupe County) during week 16. For more information on school closures, please see http://ritter.tea.state.tx.us/swineflu/schclosings.html.
U.S. Outpatient Influenza-like Illness Surveillance Network
Sixty-four 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 16. Of the 62 providers who reported seeing patients during week 16, 22 (35%) saw at least one patient with ILI. Of all patient visits during this week, 2.19% 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 5/1/2009 7:28:50 PM |
Week |
# Reporting |
Age 0-4 |
Age 5-24 |
Age 25-64 |
Age over 64 |
Total ILI |
Total Patients |
% ILI |
2008-40 |
78 |
84 |
133 |
127 |
22 |
366 |
20333 |
1.80 |
2008-41 |
78 |
114 |
163 |
124 |
19 |
420 |
20105 |
2.09 |
2008-42 |
79 |
107 |
156 |
90 |
7 |
360 |
19746 |
1.82 |
2008-43 |
79 |
120 |
152 |
106 |
20 |
398 |
19740 |
2.02 |
2008-44 |
81 |
136 |
199 |
104 |
26 |
465 |
20972 |
2.23 |
2008-45 |
78 |
110 |
111 |
122 |
27 |
370 |
20835 |
1.78 |
2008-46 |
73 |
110 |
106 |
103 |
23 |
342 |
19771 |
1.73 |
2008-47 |
75 |
137 |
143 |
122 |
19 |
421 |
19806 |
2.13 |
2008-48 |
79 |
131 |
132 |
125 |
37 |
425 |
16905 |
2.51 |
2008-49 |
77 |
143 |
159 |
153 |
24 |
479 |
20343 |
2.35 |
2008-50 |
75 |
133 |
146 |
108 |
28 |
415 |
19330 |
2.15 |
2008-51 |
69 |
172 |
177 |
175 |
24 |
548 |
17531 |
3.13 |
2008-52 |
76 |
194 |
153 |
154 |
34 |
535 |
13431 |
3.98 |
2008-53 |
77 |
176 |
141 |
165 |
46 |
528 |
15222 |
3.47 |
2009-01 |
78 |
162 |
182 |
188 |
38 |
570 |
18518 |
3.08 |
2009-02 |
77 |
178 |
287 |
235 |
41 |
741 |
20094 |
3.69 |
2009-03 |
78 |
174 |
468 |
341 |
43 |
1026 |
22951 |
4.47 |
2009-04 |
78 |
260 |
679 |
332 |
47 |
1318 |
24244 |
5.44 |
2009-05 |
73 |
282 |
883 |
465 |
40 |
1670 |
24590 |
6.79 |
2009-06 |
79 |
301 |
964 |
391 |
59 |
1715 |
24162 |
7.10 |
2009-07 |
79 |
320 |
814 |
316 |
57 |
1507 |
25873 |
5.82 |
2009-08 |
73 |
221 |
552 |
283 |
57 |
1113 |
24526 |
4.54 |
2009-09 |
76 |
194 |
422 |
244 |
71 |
931 |
22293 |
4.18 |
2009-10 |
79 |
221 |
324 |
212 |
77 |
834 |
22341 |
3.73 |
2009-11 |
75 |
167 |
268 |
178 |
58 |
671 |
19207 |
3.49 |
2009-12 |
70 |
109 |
150 |
179 |
18 |
456 |
20542 |
2.22 |
2009-13 |
69 |
114 |
141 |
163 |
16 |
434 |
18183 |
2.39 |
2009-14 |
75 |
158 |
194 |
232 |
51 |
635 |
20188 |
3.15 |
2009-15 |
68 |
86 |
129 |
144 |
19 |
378 |
19770 |
1.91 |
2009-16 |
64 |
84 |
152 |
154 |
25 |
415 |
18922 |
2.19 |
National Influenza Activity Map
The current U.S. flu weekly report may be found at http://www.cdc.gov/flu/weekly/fluactivity.htm. For more information on flu surveillance activities in the State of Texas, please visit our main surveillance page.
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