VIRUS SURVEILLANCE SUMMARY UPDATE
ending May 10, 2003-Week 19
Covey, Department of Health, Bureau of Laboratories reports that the following
week 19 (May 4-10, 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 0.99%. 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 and Polk counties. Light
to moderate influenza activity was seen in five other counties.
National report: During week
isolates (8influenza A and 1 influenza B viruses) were made from 453
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 6.4% during Week 19.
This percentage is below the epidemic threshold of 7.6% for this time.
The proportion of patient visits to sentinel physicians for influenza-like
illness (ILI) was 0.9% nationwide. State and Territorial Epidemiologists
in Massachusetts, New York, and New York City.
regional influenza activity. Twenty-two states and Washington D.C.
reported sporadic activity, and 22 states reported no influenza activity.
Since September 29, 11.8% (n=10,961) of the
83,129 specimens tested nationwide have been positive.
Three thousand three hundred and thirty-five (53%) of the 6,267 influenza
A viruses have been subtyped; 2,515 (75%) were influenza A (H1) viruses and 820
(25%) were influenza A (H3N2) viruses. Influenza
A viruses were reported more frequently than influenza B viruses (range 58% -
86%) in the New England, East North Central, Pacific, Mountain, and Mid-Atlantic
regions, and influenza B viruses were reported more frequently than influenza A
viruses (range 53% - 79%) in the West North Central, West South Central, South
Atlantic, and East South Central regions. CDC
has characterized 173 influenza A (H1N1), 55 influenza A (H1N2), 104 influenza A
(H3N2) and 222 influenza B isolates antigenically. The neuraminidase typing for
1 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/ 330/01).
Netherlands: An 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), spread to Belgium and Germany, to
swine herds in the Netherlands, and to humans.
The 83 confirmed cases of human H7N7 in the Netherlands included one
death, 79 with conjunctivitis and 13 with mild ILI. 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:
Asia: 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.