Current Trends Update: Influenza Activity -- United States
Reports of influenza activity from family physicians, state
health
departments, and collaborating diagnostic laboratories indicate
that
U.S. influenza activity is at elevated but declining levels.
Reports of influenza-like cases from the practices of sentinel
physicians* for the week ending February 26 averaged 10.4, a
decrease
from the average of 11.2 reported for the preceding week (Figure
3).
Outbreaks of influenza-like illness were reported by 14 states and
the
District of Columbia for the week ending March 8, a decrease from
the
25 states that reported outbreaks the preceding week. Seven states
indicated widespread outbreaks; seven states and the District of
Columbia indicated regional outbreaks.
Isolates of type B influenza virus have now been reported from
every state, and type A(H3N2) influenza viruses, from 31 states
during
the 1985-1986 influenza season. Incomplete totals for the week
ending
March 1 include 130 type B and 35 type A(H3N2) isolates; 187 type B
and 47 type A(H3N2) viruses were reported for the week ending
February
22. Overall, 1,714 influenza virus isolates, including 78.5% type
B
viruses and 21.5% type A(H3N2) viruses have been reported this
season.
The percentage of pneumonia and influenza (P&I) deaths reported
from the 121 U.S. cities for the week ending March 8 was 6.1%,
compared with 6.3% for the preceding week. This is the ninth
consecutive week that the P&I percentage has exceeded the
statistical
limit expected in the absence of influenza outbreaks nationwide.
Reported by State and Territorial Epidemiologists; State Laboratory
Directors; Statistical Svcs Br, Div of Surveillance and
Epidemiologic
Studies, Div of Field Svcs, Epidemiology Program Office, WHO
Collaborating Center for Influenza, Influenza Br, Div of Viral
Diseases, Center for Infectious Diseases, CDC.
*Cases reported by those members of the American Academy of Family
Physicians research panel who serve as sentinel physicians for
influenza.
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