Current Trends Update: Influenza Activity -- United States
Reports of influenza cases from family physicians' practices
and
of morbidity levels from the states and collaborating diagnostic
laboratories indicate that 1985-1986 national influenza activity
has
peaked in the United States.
Reports of influenza-like illnesses from the practices of
sentinel
physicians* for the week ending February 19 averaged 11.1 compared
with the averages of 10.9 and 11.6 reported for the preceding
weeks.
Outbreaks of influenza-like illness were reported by 25 states for
the
week ending March 1, a decrease from the total of 33 states that
reported outbreaks for the preceding week. Fourteen states
indicated
widespread outbreaks (Figure 2); 11 states and the District of
Columbia indicated regional outbreaks.
The numbers of type B virus isolates reported by the
collaborating
laboratories have peaked. Incomplete totals for the week ending
February 22 include 171 type B and 39 type A(H3N2) isolates; 249
type
B viruses and 65 type A(H3N2) viruses were reported for the week
ending February 15. Overall, 1,538 influenza virus isolates,
including 79.3% type B viruses and 20.7% 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 1 was 6.3%, the
same percentage reported for the preceding week. This is the
eighth
consecutive week the P&I percentage has exceeded the statistical
limit
expected in the absence of influenza outbreaks nationwide.
Preliminary data for the current season indicate that the age
distribution of P&I deaths is similar to that observed for the
1984-1985 influenza season.
Many outbreaks of influenza in schools have been associated
with
type B virus, and a mixed outbreak of types A(H3N2) and B viruses
in a
North Carolina college was reported earlier (1). Laboratory
evidence
of a college outbreak associated primarily with type A(H3N2) has
now
been reported from Alabama; type A(H3N2) influenza viruses were
isolated from eight of 10 ill students tested at Samford
University's
student health clinic in Birmingham during an outbreak that began
in
late January and continued into mid-February.
Reported by J Shaw, MPA, WJ Alexander, MD, Jefferson County Health
Dept, B Edwards, Birmingham Br Laboratory, Alabama State Dept of
Public Health; 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.
Editorial Note
Editorial Note:As the data above demonstrate, influenza activity is
now peaking or declining in most regions of the country. Reports
of
P&I-associated deaths typically lag several weeks behind reports of
influenza illness and viral diagnostic results. Consequently, the
P&I
percentages reported from the 121 cities may continue near the
current
levels in the near future while other indices of influenza activity
decline.
Reference
CDC. Update: influenza activity--United States. MMWR
1986;35:65-6.
*Cases reported by those members of the American Academy of Family
Physicians Research panel who serve as sentinel physicians for
influenza.
Disclaimer
All MMWR HTML documents published before January 1993 are electronic conversions from ASCII text into HTML. This conversion may have resulted in character translation or format errors in the HTML version. Users should not rely on this HTML document, but are referred to the original MMWR paper copy for the official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.
**Questions or messages regarding errors in formatting should be addressed to mmwrq@cdc.gov.
