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INFLUENZA
VIRUS SURVEILLANCE SUMMARY UPDATE
Week
ending January 11, 2003-Week 2
Carina
Blackmore, M.S. Vet. Med., Ph.D.
Florida: During week 2 (January 5-11, 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 1.6% which is lower than the activity
reported in the state last week (2.3%) and lower than the national baseline of
1.9%. Higher flu activity than expected for this time of year (>2%)
was reported by physicians in Alachua, Broward, Collier, Indian River, Monroe,
Orange, Polk, and Seminole counties. Influenza A (H1N1) was reported from Duval,
Palm Beach and Volusia counties this week. Influenza B was reported from Hillsborough, Sarasota and St
Johns counties. During the last 4 weeks influenza A (H1N1) viruses were also
detected in Collier, Indian River, Lake, Leon, Polk, and Seminole counties and
influenza B in Okaloosa County. Since December 15 reports of influenza A of
unknown subtype have come from Brevard and Orange counties and positive rapid
tests from Alachua, Duval, Indian River, Miami-Dade and Pinellas counties.
National report: Sixty-seven isolates (25 influenza A and 42 influenza B viruses) were made from 1,213 specimens
tested by the World Health Organization (WHO) and National
Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating
laboratories this week. Since
September 29, 2.2% (n=614) of the 27,861 specimens tested nationwide have been
positive. Fifty-three (32%) of the 164 influenza A viruses have been subtyped;
42 were influenza A H1 viruses and 11 were influenza A (H3N2). Influenza A and
influenza B viruses have been identified in 14 states (Arizona, California,
Colorado, Florida, Indiana, Louisiana, Missouri, Nebraska, New York, North
Carolina, Oklahoma, South Carolina, Texas, Virginia and Wisconsin). Fifteen
states (Alabama, Connecticut, Delaware, Hawaii, Illinois, Massachusetts,
Michigan, Minnesota, New Jersey, Oregon, South Dakota, Tennessee, Utah, Vermont
and Washington have reported only influenza A viruses, and 8 states (Alaska,
Arkansas, Kansas, Kentucky, Montana, Nevada, New Hampshire and West Virginia)
have reported only influenza B viruses. CDC has characterized 11 influenza A
(H1N1), 1 influenza A (H1N2), 4 influenza A (H3N2) and 32 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 1.6% nationwide. The State and Territorial Epidemiologists reported flu
outbreaks in 9 states (Arkansas, Kansas, Missouri, Nebraska, New York, Oklahoma,
Tennessee, Texas and Virginia). Sporadic influenza activity was reported from 33
states. The proportion of deaths attributed to pneumonia and influenza as
reported by the vital statistics offices of 122 U.S. cities was 7.3% during week
2. This percentage is below the epidemic threshold of 8.1%
for this time.
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