VIRUS SURVEILLANCE SUMMARY UPDATE
ending November 2, 2002-Week 44
Blackmore, M.S. Vet. Med., Ph.D.
During week 44
(October 27-November 2, 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 low (1.1%). Higher flu activity than expected for this time of year (>2%)
was reported by physicians in Okaloosa, Orange and Palm Beach counties. The
second positive rapid flu test was reported from Miami-Dade County this week.
Earlier this season an influenza A(H1N1) outbreak was confirmed in Holmes
report: Four influenza isolates (2 unsubtyped influenza A
viruses and 2 influenza B viruses) were made from the 884 specimens tested by
the World Health Organization (WHO) and National Respiratory and Enteric Virus
Surveillance System (NREVSS) collaborating laboratories this week. Since September 29, 0.2% (n=10)
of the 5,355 specimens tested nationwide have been positive. Influenza A
activity has been detected in Florida, Louisiana, New York, North Carolina and
South Carolina. Influenza B isolates have been identified in New York and North
Carolina. CDC has characterized one influenza A (H1N2) isolate antigenically.
Both the hemagglutinin (H) and neuraminidase (N) proteins of this reassorted
strain are similar to H and N proteins in the vaccine strains. The proportion of
patient visits to sentinel physicians for influenza-like illness (ILI) was 1.2%
nationwide, which is below the national baseline of 1.9%. AN ILI outbreak was
reported from Louisiana. Sporadic influenza activity was reported from 14 states
(Alabama, Colorado, Florida, Georgia, Indiana, Kansas, Kentucky, Maine,
Nebraska, Nevada, New Mexico, Tennessee, 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 6.7% during week 44. This percentage is
below the epidemic threshold of 7.1% for this time.