Epidemiologic Notes and Reports Update: Influenza Activity -
- United States
Influenza viruses have been isolated in all states and the
District of Columbia during the 1986-87 season; 49 states* and the
District of Columbia have reported at least one isolate of
influenza
type A/Taiwan/86(H1N1). Most states are now reporting declining
activity. The peak level of outbreak activity occurred in
mid-January
when 28 states reported outbreaks. Activity this season was below
the
peak of the previous winter when 37 states reported outbreaks for 1
week in February. For the week ending February 21, only two
states**
reported widespread outbreaks of influenza-like illness, and 11
statesS and Puerto Rico reported regional outbreaks.
The percentage of deaths associated with pneumonia and
influenza
(P&I) reported from the 121 cities reporting regularly to CDC
reached
a peak of 6.2% for the week ending January 24, 1987. Although this
percentage exceeded the epidemic threshold (Figure 1), it was below
the peak reported for the previous two epidemic seasons, in which
the
percentage of deaths associated with P&I reached 7.2% and 6.6%
respectively. This mortality surveillance system indicates a
slight
increase in P&I deaths at a time corresponding with the peak of
influenza A/Taiwan/86 activity.
Reported by State and Territorial Epidemiologists; State Laboratory
Directors; WHO Collaborating Center for Influenza, Influenza Br,
Div
of Viral Diseases, Center for Infectious Diseases, CDC.
*Wyoming has not reported A/Taiwan/86 influenza.
**Idaho and South Dakota.
SArkansas, Connecticut, Iowa, Kansas, Mississippi, Missouri,
Nebraska,
North Dakota, Pennsylvania, Texas, and Wisconsin.
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