Surveillance

Influenza
(Flu)
ICD-9 487; ICD-10 J10,11
Related Topics: Protecting Yourself During the Cold and Flu Season, Avian Flu, Vaccine Preventable Diseases, Asthma and SARS

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2008 - 2009 Texas Influenza Surveillance Information

Current Flu Activity Report in PDF Format

Influenza Surveillance Report for MMWR Week 18

The influenza (flu) activity level for Texas for the week ending May 9, 2009 was “widespread.” During week 18, 62 (3.4%) 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 18. HSRs 7 and 8 reported an increased level of flu activity compared to week 17. HSRs 1, 2/3, and 4/5N reported the same level of flu activity compared to week 17. HSRs 9/10 and 11 reported a decreased level of flu activity compared to week 17. HSR 6/5S could not determine the level of flu activity compared to week 17. 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 18, seven hospital laboratories and public health agencies across Texas reported conducting a total of 1,842 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 1,287 antigen detection tests that were performed, 44 were positive for influenza A/not subtyped and 5 were positive for influenza B. The positive results were reported from Bell, Bexar, Collin, Dallas, Lubbock, and Tarrant counties.

A total of 25 reports of PCR- or culture-confirmed influenza were received from public health laboratories, Scott & White Memorial Hospital in Temple, Texas Children's Hospital in Houston, NREVSS, the United States Air Force School of Aerospace Medicine (USAFSAM), and other sources for the following counties during week 18 (May 3-May 9):

`Influenza A/H1 (seasonal)`	`Influenza A/H3`	`Influenza A/not subtyped`	`Influenza B`
Bexar County	(none)	Bell County	Bell County (8)
		Bexar County (3)	Galveston County
		Dallas County (3)	McLennan County
		Gregg County
		Harris County (2)
		Hidalgo County (2)
		Taylor County
		Travis County

Positive point-of-care rapid tests for influenza were reported by providers throughout the state (see county map below).

Novel Influenza A Virus Infections

A total of 19 cases of influenza A H1N1 swine confirmed by the CDC have been reported with a known illness onset in week 18 (May 3-May 9) for the following counties (listed by patient county of residence):

`Influenza A H1N1 swine`
Atascosa County
Denton County
Hood County
Nueces County (3)
Tarrant County (13)

Additional specimens have been identified by PCR testing as positive for unsubtypeable influenza A; these specimens are being forwarded to CDC or state labs for further study. This information is subject to change as more reports are received. Case 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 50 influenza isolates [20 influenza A/H1, 8 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 [8]

All 8 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]

Fifteen of the influenza B viruses were characterized as belonging to the B/Victoria lineage.

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, 22 seasonal influenza A/H1 isolates, 7 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 (%)
	Isolates Tested (n)	Oseltamivir	Zanamivir	Isolates Tested (n)	Adamantanes
Influenza A/H1	22	22 (100%)	0 (0)	22	0 (0)
Influenza A/H3	7	0 (0)	0 (0)	7	7 (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

One influenza-associated pediatric fatality in a Texas resident was reported during week 18. The death occurred during MMWR week 14 (week ending April 11, 2009) in a 13-year-old resident of Health Service Region 3 with significant underlying medical conditions. A specimen obtained from the child was positive for influenza B by viral culture. It is not known whether the child was vaccinated for influenza for the current season. Texas has reported eleven influenza-associated pediatric fatalities during the 2008-09 influenza season.

School Closures and Institutional Outbreaks

New school closures were reported in HSRs 2/3 (Collin, Dallas, Denton, Jack, Kaufman, Parker, Tarrant, Taylor, and Wise counties); 6 (Brazoria, Fort Bend, Galveston, Harris, Liberty, and Montgomery counties); 7 (Travis County); 8 (Bexar and Val Verde counties); and 11 (Brooks, Cameron, Hidalgo, Jim Wells, Nueces, and Webb counties) during week 18. Not all districts and/or schools within a district were closed in the counties mentioned. Several of the schools that closed in week 18 or in previous weeks reopened during week 18, partially due to changes in CDC guidance for school closures. 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

Fifty-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 18. Of the 53 providers who reported seeing patients during week 18, 34 (64%) providers saw at least one patient with ILI. Of all patient visits during this week, 3.44% 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 5/12/2009 10:45:42 AM
`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	76	167	268	178	58	671	19314	3.47
2009-12	71	109	150	179	18	456	20622	2.21
2009-13	71	114	141	163	16	434	18356	2.36
2009-14	78	158	194	232	51	635	20522	3.09
2009-15	75	92	135	152	23	402	20738	1.94
2009-16	81	116	188	163	28	495	21228	2.33
2009-17	69	229	554	342	44	1169	24392	4.79
2009-18	54	145	320	183	30	678	19683	3.44