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INFLUENZA
VIRUS SURVEILLANCE SUMMARY UPDATE
Week
ending November 30, 2002-Week 48
Carina
Blackmore, M.S. Vet. Med., Ph.D.
Florida: During week 48 (November 24-30, 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 1.6%. 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
Broward, Duval, Leon, Orange, Palm Beach, Polk and Sarasota counties. Two
influenza isolates (influenza A (H1N1) from Leon County and influenza A (H3N2)
from Indian River county) were reported this week. Influenza cases confirmed by
rapid tests were also reported from Miami-Dade County. Earlier this season,
influenza viruses (Influenza A (H1N1)) were detected in Broward and Holmes
counties.
National report: Seven isolates (3 influenza A and 4
influenza B viruses) were made from 519 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=55)
of the 10,691 specimens tested nationwide have been positive. Eight (35%) of the
24 influenza A viruses have been subtyped; 7 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, Oregon, South Carolina,
Texas and Virginia. Influenza B isolates have been identified in Louisiana, New
York, Oklahoma, South Carolina and Texas. CDC has characterized three influenza
A (H1N1), 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 1.4% nationwide. Outbreaks were reported from
Colorado, Tennessee and Texas. Sporadic influenza activity was reported from 18
states (Alabama, Florida, Georgia, Indiana, Kansas, Louisiana, Maine, Michigan,
Missouri, Nebraska, Nevada, New Mexico, New York, Oklahoma, Oregon, Utah,
Vermont and West Virginia). 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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