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 19

The influenza (flu) activity level for Texas for the week ending May 16, 2009 was “widespread.” During week 19, 27 (4.2%) 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 19. HSRs 7 and 8 reported the same level of flu activity compared to week 18. All other HSRs reported a decreased level of flu activity compared to week 18. 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 19, seven hospital laboratories and public health agencies across Texas reported conducting a total of 639 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 593 antigen detection tests that were performed, 22 were positive for influenza A/not subtyped and 4 were positive for influenza B. The positive results were reported from Dallas, Harris, Lubbock, and Nueces counties.

A total of 4 reports of PCR- or culture-confirmed seasonal influenza were received from 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 19 (May 10-May 16):

`Influenza A/H1 (seasonal)`	`Influenza A/H3`	`Influenza A/not subtyped`	`Influenza B`
(none)	(none)	Bexar County	(none)
		Dallas County
		Harris County (2)

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

Novel Influenza A Virus Infections

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/h1n1flu/) 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

No influenza-associated pediatric fatalities in Texas residents were reported during week 19. Texas has reported eleven influenza-associated pediatric fatalities during the 2008-09 influenza season.

School Closures and Institutional Outbreaks

A new school closure was reported in HSR 6 (Harris County) during week 19. Several of the schools that closed in week 18 or in previous weeks reopened during week 19, 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

Forty-six 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 19. Of the 42 providers who reported seeing patients during week 19, 24 (57%) providers saw at least one patient with ILI. Of all patient visits during this week, 3.51% 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 5/22/2009 1:33:07 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	80	120	152	106	20	398	19857	2.00
2008-44	82	136	199	104	26	465	20972	2.22
2008-45	79	110	111	122	27	370	20959	1.77
2008-46	74	110	107	103	23	343	19890	1.72
2008-47	76	137	143	122	19	421	19907	2.11
2008-48	80	132	132	125	37	426	17012	2.50
2008-49	78	143	159	153	24	479	20446	2.34
2008-50	76	133	146	108	28	415	19450	2.13
2008-51	70	172	177	175	24	548	17663	3.10
2008-52	77	194	153	154	34	535	13509	3.96
2008-53	78	176	141	165	46	528	15329	3.44
2009-01	79	162	182	188	38	570	18646	3.06
2009-02	78	178	287	235	41	741	20222	3.66
2009-03	79	174	468	341	43	1026	23058	4.45
2009-04	79	260	679	333	47	1319	24350	5.42
2009-05	74	282	884	467	40	1673	24734	6.76
2009-06	80	301	965	392	59	1717	24320	7.06
2009-07	80	320	816	316	57	1509	26024	5.80
2009-08	74	221	552	283	57	1113	24664	4.51
2009-09	77	194	423	245	71	933	22428	4.16
2009-10	80	221	325	212	77	835	22635	3.69
2009-11	77	167	269	178	58	672	19656	3.42
2009-12	72	109	150	179	18	456	20910	2.18
2009-13	73	114	143	163	16	436	18660	2.34
2009-14	80	158	197	234	51	640	20843	3.07
2009-15	77	92	136	156	23	407	21124	1.93
2009-16	84	116	188	163	28	495	21577	2.29
2009-17	73	229	554	348	44	1175	24699	4.76
2009-18	64	165	344	186	31	726	21233	3.42
2009-19	46	96	244	185	26	551	15700	3.51