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INFLUENZA
VIRUS SURVEILLANCE SUMMARY UPDATE
Week
ending November 23, 2002-Week 47
Carina
Blackmore, M.S. Vet. Med., Ph.D.
Florida:
During week 47
(November 17-23, 2002) influenza activity, calculated based on the proportion of
patients with influenza-like illness (ILI) seeking care by physicians
participating in the Florida Sentinel Physicians Surveillance Network was 1.3%.
Although the activity is increasing over time it is below the national baseline
of 1.9%. Higher flu activity than expected for this time of year (>2%)
was reported by physicians in Duval, Leon. Okaloosa, Orange, Palm Beach, Polk
and Seminole counties. Six influenza cases confirmed by rapid tests were
reported from Miami-Dade this week. Influenza viruses (Influenza A (H1N1)) have
also been detected in Broward and Holmes counties this season.
National
report:
Twenty-one isolates (5 influenza A and 16 influenza B viruses) were made from 923 specimens
tested by the World Health Organization (WHO) and National
Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating
laboratories this week. Since
September 29, 0.5% (n=47) of the 10,036 specimens tested nationwide have been
positive. Seven (35%) of the 20 influenza A viruses have been subtyped; 6 were
influenza A H1 viruses and 1 was an influenza A (H3N2). Influenza A activity has
been detected in Florida, Hawaii, Louisiana, Nebraska, New York, North Carolina
and South Carolina and Virginia. Influenza B isolates have been identified in
Louisiana, New York, South Carolina and Texas. CDC has characterized one
influenza A (H1N2), one influenza A (H3N2) and five influenza B isolates
antigenically. All strains were similar antigenically to corresponding vaccine
strains. The proportion of patient visits to sentinel physicians for
influenza-like illness (ILI) was 1.3% nationwide. Outbreaks were reported from
Louisiana and Texas. Sporadic influenza activity was reported from 18 states
(Colorado, Florida, Georgia, Hawaii, Indiana, Kansas, Kentucky, Maine, Michigan,
Missouri, Nebraska, Nevada, New Mexico, Pennsylvania, Tennessee, Utah, West
Virginia and Wyoming). The proportion of deaths attributed to pneumonia and
influenza as reported by the vital statistics offices of 122 U.S. cities was
7.1% during week 47. This percentage is
below the epidemic threshold of 7.4% for this time.
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