Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file

Weekly Report: Influenza Summary Update

Week ending May 15, 2004-Week 19

Error processing SSI file

The following information may be quoted:

Synopsis:

Influenza activity remained low during the week of May 9-15, 2004. The percentage of patient visits for influenza-like illness (ILI) has remained below the national baseline (2.5%) since the week ending January 17. During week 19, mortality due to pneumonia and influenza (P&I) remained below the epidemic threshold (7.4%). None of the 477 specimens collected from throughout the United States and tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories were positive for influenza. Six states and Puerto Rico reported sporadic activity; and 43 states, the District of Columbia, New York City, and Guam reported no influenza activity.

Laboratory Surveillance*:

During week 19, WHO and NREVSS laboratories reported no positive results for the 477 specimens tested for influenza viruses.

Since September 28, 2003, WHO and NREVSS laboratories have tested 126,021 specimens for influenza viruses, of which 24,641 (19.6%) were positive. Of these, 24,415 (99.1%) were influenza A viruses, and 226 (0.9%) were influenza B viruses. Of the 24,415 influenza A viruses, 7,213 (29.5%) have been subtyped; 7,211 (99.9%) were influenza A (H3N2) viruses and 2 (0.1%) were influenza A (H1) viruses.

Influenza Virus Isolated


View Chart Data

Antigenic Characterization:

CDC has antigenically characterized 976 influenza viruses collected by U.S. laboratories since October 1, 2003: three influenza A (H1) viruses, 918 influenza A (H3N2) viruses, and 55 influenza B viruses. The hemagglutinin proteins of the influenza A (H1) viruses were similar antigenically to the hemagglutinin of the vaccine strain A/New Caledonia/20/99. Of the 918 influenza A (H3N2) isolates that have been characterized, 106 (11.5%) were similar antigenically to the vaccine strain A/Panama/2007/99 (H3N2), and 812 (88.5%) were similar to the drift variant, A/Fujian/411/2002 (H3N2). Fifty of the influenza B viruses belonged to the B/Yamagata lineage and were similar antigenically to B/Sichuan/379/99. Five influenza B viruses belonged to the B/Victoria lineage and were similar antigenically to the vaccine strain B/Hong Kong/330/2001.

Pneumonia and Influenza (P&I) Mortality Surveillance:

During week 19, 6.1% of all deaths reported by the vital statistics offices of 122 U.S. cities were due to pneumonia and influenza. This percentage is below the epidemic threshold of 7.4% for week 19.

Pneumonia And Influenza Mortality

View Full Screen

Influenza-like Illness Surveillance *:

The percentage of patient visits to approximately 1,000 U.S. sentinel providers nationwide for ILI was 0.5%** during week 19. This indicator has been below the national baseline of 2.5% since the week ending January 17. The percentage of patient visits for ILI in each of the nine surveillance regions*** was below 1.1%. Due to wide variability in regional level data, it is not appropriate to apply the national baseline to regional level data.

Bar Chart for Influenza-like Illness
View Chart Data | View Full Screen

Influenza Activity as Assessed by State and Territorial Epidemiologists**:

Sporadic activity was reported in 6 states (Colorado, Hawaii, Massachusetts, Nevada, Ohio, and Utah) and Puerto Rico. All other states, New York City, the District of Columbia, and Guam reported no influenza activity. Oklahoma did not report.

U. S. map for Weekly Influenza Activity
View Full Screen

--------------------------------------------------------------------------------

* Reporting is incomplete for this week. Numbers may change as more reports are received.

** The national and regional percentage of patient visits for ILI is weighted on the basis of state population.

*** Surveillance Regions: New England (Connecticut, Maine, Massachusetts, New Hampshire, Vermont, Rhode Island); Mid-Atlantic (New Jersey, New York City, Pennsylvania, Upstate New York); East North Central (Illinois, Indiana, Michigan, Ohio, Wisconsin); West North Central (Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota); South Atlantic (Delaware, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, Washington, D.C., West Virginia); East South Central (Alabama, Kentucky, Mississippi, Tennessee); West South Central (Arkansas, Louisiana, Oklahoma, Texas); Mountain (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming); Pacific (Alaska, California, Hawaii, Oregon, Washington)

Report prepared May 20, 2004

Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file