Whatcom County Weekly Influenza Report
2009 Pandemic H1N1 Influenza Season
Week 38, ending Saturday September 26, 2009

Summary:

Whatcom County
Influenza activity in Whatcom County has been stable, with ongoing reporting of hospitalized cases and of positive laboratory results in outpatients. School absenteeism has returned to baseline after a previous week of a couple of local schools reporting high absenteeism. No specific outbreaks were reported during the report week.

Washington State
DOH reported as of September 23, 2009:
· During April 19 through September 23, 2009, the Washington State Department of Health received reports of 181 hospitalized and 16 deceased persons confirmed to be infected with 2009 H1N1 influenza virus. An additional 4 individuals were hospitalized in week 37 with influenza infection for which the influenza type was unknown.
· Among sentinel providers in Washington, the proportion of patient visits for influenza-like illness has increased over the past two weeks.
· The influenza activity in Washington was classified as widespread. Influenza activity is currently elevated in over half of the regions in the state.
National
The CDC reported that for the week ending 9/19/09 (Week 37):
· 2,326 (23.9%) specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories and reported to CDC/Influenza Division were positive for influenza.
· 99% of all subtyped influenza A viruses being reported to CDC were 2009 influenza A (H1N1) viruses.
· The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.
· Three influenza-associated pediatric deaths were reported and all three were associated with 2009 influenza A (H1N1) virus infection.
· The proportion of outpatient visits for influenza-like illness (ILI) was above the national baseline. Regions 2 through10 reported ILI above region-specific baseline levels; only Region 1 was below its’ region-specific baseline.
· Twenty-six states reported geographically widespread influenza activity, 11 states reported regional influenza activity, 12 states, the District of Columbia, and Puerto Rico reported local influenza activity, one state and Guam reported sporadic influenza activity, and the U.S. Virgin Islands did not report.

Influenza Hospitalizations and Deaths

Influenza cases (hospitalized and fatal) in Whatcom County, Week 38, September 20 to September 26:

Since 8/30/09, 5 hospitalizations and 0 deaths including 2 hospitalizations reported this report week.

All cases of hospitalized patients with positive laboratory tests for influenza are reportable, as are fatalities with laboratory evidence of influenza.

Pneumonia & Influenza Mortality

The proportion of deaths associated with influenza and pneumonia is a standard indirect indicator of influenza activity. The table includes counts of all death certificates filed in Whatcom County during the report week and those that list influenza or pneumonia as a cause of death or contributing factor.

Week 35 36 37 38
End date 9/5/09 9/12/09 9/19/09 9/26/09
Total Deaths 31 22 16 30
P&I Deaths 0 0 1 1
Percent of all deaths due to P&I 0% 0% 6% 3%

The CDC chart for Pneumonia and Influenza Mortality can viewed at http://www.cdc.gov/flu/weekly/

Outpatient Visits

Western Washington University Student Health Center is a CDC Sentinel Influenza Surveillance site and reports weekly the number of patients seen and number of those with influenza-like illness (ILI).

For Report Week 38, ending 9/26/09, WWU reported seeing 351 students, 5 with ILI.

Laboratory Data

The total number of influenza tests and the percentage positive for influenza is an indicator of influenza activity in the community. Respiratory Syncytial Virus testing provides an indicator of other causes of viral respiratory illness in the community.

PeaceHealth Laboratories - Bellingham

Week 35 36 37 38
End date 9/5/09 9/12/09 9/19/09 9/26/09
Influenza tests
Total n/a 67 46 62
% Positive A n/a 9 2.2 6.5
% Positive B n/a 0 0 0

RSV tests
Total n/a 5 2 9
% Positive n/a 0 0 0

School Absenteeism

School absenteeism is an indirect measure of influenza activity. Absenteeism increases during influenza season and during outbreaks, but may be due to causes other than influenza.

Bellingham School District reports daily absenteeism for all schools in the district to the health department. Eight other private and public sentinel schools within the county report absenteeism twice a week. All schools in the county are required to report to the health department when absenteeism exceeds 10%.

Bellingham School District Daily and Weekly Absenteeism

Day 9/21/09 9/22/09 9/23/09 9/24/09 9/25/09
% Absent 7.6 6.1 6.0 6.4 6.8

Week 38
End date 9/26/09
Average % Absent 6.6

Sentinel School Semiweekly Absenteeism (n=8)

Day 9/22/09 9/24/09
% Absent n/a 4.4

Elevated Absenteeism in Schools

Day 9/21/09 9/22/09 9/23/09 9/24/09 9/25/09
>10% absent 0 0 0 0 0
>20% absent 0 0 0 0 0
>30% absent 0 0 0 0 0

Links for other influenza weekly status reports

WA State Department of Health Weekly Influenza Updates
www.doh.wa.gov/EHSPHL/Epidemiology/CD/fluupdate.pdf

BC Centre for Disease Control Weekly H1N1 Alert
www.bccdc.ca/resourcematerials/newsandalerts/healthalerts/H1N1FluVirusHumanSwineFlu.htm

Centers for Disease Control (CDC) Weekly Flu View
www.cdc.gov/flu/weekly

World Health Organization Pandemic (H1N1) 2009 Situation Updates
www.who.int/csr/disease/swineflu/updates/en/index.html

For local information go to http://www.em.whatcomcounty.org