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INFLUENZA
VIRUS SURVEILLANCE SUMMARY UPDATE
Week
ending January 4, 2003-Week 1
Carina
Blackmore, M.S. Vet. Med., Ph.D.
Florida: During week 1 (December 29, 2002- January 4, 2003)
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 2.3% which is higher than
the national baseline of 1.9%. Higher
flu activity than expected for this time of year (>2%) was reported by
physicians in Alachua, Duval, Indian River, Lake, Monroe, and Polk counties.
Influenza A (H1N1) was reported from Leon County this week. Influenza A of
unknown subtype was reported from Hillsborough and Orange counties and influenza
B was reported from Orange County. Positive rapid tests were reported from
Alachua, Hillsborough and Indian River counties. Earlier this season, influenza
A (H1N1) viruses were detected in Broward, Holmes, Indian River Lake, Leon and
Seminole counties, influenza A (H3N2) in Indian River County and influenza B in
Leon and Okaloosa County. Influenza A of unknown subtype have been reported from
Brevard and Duval counties and positive rapid tests from Bay, Broward, Duval,
Miami-Dade and Pinellas counties.
National report: Twenty-five isolates (12 influenza A and 13 influenza B viruses) were made from 1,147 specimens
tested by the World Health Organization (WHO) and National
Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating
laboratories this week. Since
September 29, 1.3% (n=273) of the 23,976 specimens tested nationwide have been
positive. Twenty-four (27%) of the 90 influenza A viruses have been subtyped; 18
were influenza A H1 viruses and 6 were influenza A (H3N2). Influenza A and
influenza B viruses have been identified in detected in Arizona, California,
Florida, Indiana, Louisiana, Missouri, Nebraska, New York, North Carolina, South
Carolina, Texas and Virginia. Hawaii, Massachusetts, Minnesota, New Jersey,
Oregon, South Dakota, Washington and Wisconsin have reported only influenza A
viruses, and Arkansas, Kansas, Nevada, New Hampshire, and Oklahoma have reported
only influenza B viruses. CDC has characterized eleven influenza A (H1N1), one
influenza A (H1N2), four influenza A (H3N2) and twenty-six influenza B isolates
antigenically. All strains were similar to corresponding vaccine strains. The
proportion of patient visits to sentinel physicians for influenza-like illness (ILI)
was 2.0% nationwide. The State and Territorial Epidemiologists reported flu
outbreaks in 7 states (Arkansas, Kansas, New york, Oklahoma, Tennessee, Texas
and Virginia). Sporadic influenza activity was reported from 31 states. The
proportion of deaths attributed to pneumonia and influenza as reported by the
vital statistics offices of 122 U.S. cities was 6.8% during week 1. This percentage is below the epidemic threshold of 8.0%
for this time.
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