Influenza activity in the 1981-1982 influenza season continues
to
be at a relatively low level. Isolations of influenza type B virus
have been reported by 23 states (including the first reports this
season from Alaska, Maryland, Missouri, and Oklahoma); 8 of these
states have also reported isolating type A(H1N1) virus, and 1
state,
New Jersey, has reported isolating type A(H1N1) virus only (Figure
4). From October 1981 through February 1982, the total number of
viruses isolated by laboratories participating in the nationwide
reporting system was about 200. This compared with about 1,500
isolates reported by the participating laboratories in the United
States in each of the 3 preceding winters, reflecting the generally
low levels of morbidity throughout the country this winter.
The actual extent of virus transmission may not be fully
indicated
by nationwide laboratory reports in the absence of major outbreaks
which cause concern to public health authorities and physicians.
Thus, in Houston, Texas, where all patients with acute febrile
respiratory illness are cultured for viral isolates when seen by a
group of sentinel physicians and clinics participating in a
long-term
virus surveillance system, more than 500 isolates of influenza
virus
were obtained through February 1982. Preliminary analysis of a
random
sample from a survey of Houston city schools indicates that even
during the peak of virus isolations in Houston during the third
week
of February, when 41% (114/277) of cultures were positive for
influenza, only moderate increases of overall school absenteeism
rates
occurred in the Houston Independent School District. This pattern
of
moderate increases is consistent with findings in other communities
where influenza viruses have been isolated in smaller numbers than
in
Houston.
The ratio of pneumonia-influenza related deaths has barely
exceeded the statistically established threshold level in the
1981-1982 season. In contrast, the ratio consistently exceeded the
threshold level by a wide margin for a substantial period during
each
of the 2 previous winters (Figure 5).
Although most isolates of influenza virus this season were
obtained from children and young adults, 1 outbreak of influenza
has
been reported in a nursing home in St. Louis County, Missouri,
where
about 34 of 120 residents experienced an influenza-like illness
during
1 week. On March 4, shortly after the outbreak began, influenza
type
B virus was isolated from 8 elderly patients.
Reported by P Glezen, MD, Influenza Research Center, Baylor
University, J Craven, MD, Houston City Health Department, R
Beauchamp,
MD, C Webb, Jr, MD, State Epidemiologist, Texas State Dept of
Health;
KL Scruggs, MD, St. Louis County, WC Banton, II, MD, District 7, ER
Spurrier, PhD, D Donnell, Jr, MD, State Epidemiologist, Missouri
Dept
of Social Svcs; other state laboratory directors and state
epidemiologists; Field Services Division, Consolidated Surveillance
and Communications Activity, Epidemiology Program Office, Influenza
Br, Viral Diseases Div, Center for Infectious Diseases, CDC.
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