VIRUS SURVEILLANCE SUMMARY UPDATE
ending May 3, 2003-Week 18
Covey, Department of Health, Bureau of Laboratories reports that the following
During week 18 (April 27 May 3, 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 0.86%. This is lower than the national baseline of
1.9%. Higher flu activity than expected for this time of year (>2%)
was reported by physicians in Indian River, Leon and Polk counties. Light to moderate influenza activity was seen in four other
report: During week 18,
isolates (10influenza A and 4 influenza B viruses) were made from 569 specimens tested by the World
Health Organization (WHO) and National Respiratory and Enteric Virus
Surveillance System (NREVSS) collaborating laboratories this week.
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
18. This percentage is below the
epidemic threshold of 7.7% for this time. The proportion of patient visits to
sentinel physicians for influenza-like illness (ILI) was 0.7% nationwide. The
State and Territorial Epidemiologists in
Massachusetts reported regional influenza activity. Sporatic activity was
reported in 29 states, New York City and Washington, D.C.
Seventeen states reported no influenza activity.
the past 3 weeks (weeks 16-18), 61.5% of the 13 specimens tested for influenza in the
New England region were positive, and less than 50% of the specimens tested for
influenza in the remaining eight influenza surveillance regions were positive.
September 29, 11.7% (n=10,686) of the 91,102 specimens tested nationwide have been
positive. Three thousand one
hundred and eighty-eight (53%) of the 6,068 influenza A viruses have been
subtyped; 2,396 (75%) were influenza A (H1) viruses and 792 (25%)
were influenza A (H3N2) viruses. Laboratory
confirmed influenza has been reported from all 50 states.
Influenza A viruses were reported more frequently than influenza B
viruses (range 57% - 86%) in the New England, East North Central, Mountain,
Pacific, and Mid-Atlantic regions, and influenza B viruses were reported more
frequently than influenza A viruses (range 54% - 80%) in the West North Central,
West South Central, South Atlantic, and East South Central regions.
However, during the past 3 weeks (weeks 16-18), influenza A viruses were
reported at least as frequently as influenza B viruses in all nine surveillance
regions. CDC has characterized 173
influenza A (H1N1), 55 influenza A (H1N2), 91 influenza A (H3N2) and 222
influenza B isolates antigenically. The neuraminidase typing for one H1 virus is
pending. All influenza A
strains were similar to corresponding vaccine strains. One influenza B strain
was more similar to B/Shizuoka/15/01 than to the vaccine strain (B/Hong Kong/
in April the first fatal human case of influenza A (H7N7).
outbreak of highly pathogenic avian influenza A (H7N7 HPAI) in chickens began
during February 2003 in the Netherlands and, despite control measures
(restricting transport and culling), has spread to Belgium and Germany, to swine
herds in the Netherlands, and humans. Of
the 83 confirmed cases of human H7N7 in the Netherlands, 79 exhibited
conjunctivitis and 13 had mild ILI. Possible
human-to-human transmission was suggested when three family members of two
poultry workers fell ill with a minor respiratory disease.
The WHO Influenza Collaborating Centers are to begin production of a
reagent kit to identify H7N7 viruses. More
information about this outbreak of H7N7 HPAI can be found at:
An avian flu virus strain, influenza A (H5N1), was
recovered from two influenza cases in Hong Kong earlier this year. CDC has
issued recommendations on increased influenza surveillance in the United States.
Of particular importance is to consider influenza cultures on patients,
with recent travel histories to Asia, who are hospitalized with unexplained
pneumonia, acute respiratory distress syndrome or severe respiratory illness.
* Reporting is incomplete for this week. Numbers
may change as more reports are received.