Centers for Disease Control and Prevention
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Influenza Summary Update
(Week ending December 9, 2000-Week 49)
The following information may be quoted:
Synopsis: During
week 49 (December 3-9, 2000), 39 of the specimens tested by WHO and NREVSS laboratories
were positive for influenza type A virus and 12 were positive for influenza type B virus. The proportion of patient visits to sentinel
physicians for influenza-like illness was within baseline levels of 0% to 3% in the United
States overall and in all 9 surveillance regions. The
proportion of deaths attributed to pneumonia and influenza was 7.2%. This percentage is below the epidemic threshold
for this time of year. Five state and territorial health departments
reported regional influenza activity, 31 reported sporadic activity, and 13 reported no
influenza activity.
U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus
Surveillance System (NREVSS) Collaborating Laboratory Reports*:
During
week 49, WHO and NREVSS laboratories reported 870 specimens tested for influenza viruses,
of which 51 (6%) were positive. Thirty-three
were influenza A (H1N1) viruses, 6 were unsubtyped influenza A viruses, and 12 were
influenza B viruses.
Antigenic
Characterization of Viral Isolates: CDC
has antigenically characterized 22 influenza viruses received from U.S. laboratories since
October 1: 1 influenza A (H3N2) virus, 19 influenza A (H1N1) viruses, and 2 influenza B
viruses. These viruses are antigenically
similar to vaccine strains A/Panama/2007/99 (H3N2), A/New Caledonia/20/99 (H1N1), and
B/Beijing/184/93, respectively.
Pneumonia and Influenza (P&I) Mortality: During
week 49, the percentage of all deaths due to P&I as reported by the vital statistics
offices of 122 U.S. cities was 7.2%. This
percentage is below the epidemic threshold of 8.1% for week 49.
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Influenza Morbidity Reports from U.S. Sentinel Physicians *: During week 49, 1% of patient visits to U.S. sentinel physicians were due to influenza-like illness (ILI). The percentage of ILI was within baseline levels of 0% to 3% in all 9 surveillance regions.
Influenza Activity as Assessed by State and
Territorial Epidemiologists**: Influenza
activity was reported as regional in 5 states (Georgia, Hawaii, Kentucky, Tennessee, and
Texas) and sporadic in 31 states (Alabama, Alaska, Arizona, Arkansas, California,
Colorado, Florida, Illinois, Indiana, Iowa, Kansas, Louisiana, Maine, Michigan,
Mississippi, Missouri, Nevada, New Mexico, North Carolina, Ohio, Oklahoma, Oregon, Rhode
Island, South Carolina, South Dakota, Utah, Virginia, Washington, West Virginia,
Wisconsin, and Wyoming). Thirteen states
reported no influenza activity and 1 state did not report.
* Reporting is incomplete for this week. Numbers
may change as more reports are received.
**
Influenza activity is defined as influenza-like illness and/or culture-confirmed
influenza.
Appendix I: 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