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Update: Influenza Activity -- United States -- and the Role of
Rapid Virus Typing in Improving Amantadine Use
Between December 30, 1985, and January 13, 1986, 27 (36%) of 74
elderly residents in a San Joaquin County, California, nursing home
developed influenza-like illnesses.* Influenza virus type B was
isolated from two of the five ill residents tested. This is the
first
report of a nursing-home outbreak this season associated with type
B
virus; an earlier report described outbreaks associated with type
A(H3N2) virus in health-care facilities for elderly patients in New
York (1).
Nine additional states have reported their first influenza
virus
isolations for the season. Type B virus has been reported from
Alabama, Florida, Idaho, Louisiana, Missouri, New Jersey, and
Oregon;
type A(H3N2) virus has been reported from New Mexico and Oklahoma.
In
New York and Nevada, where type A(H3N2) virus had been reported
previously this season, type B virus was also reported. The
season's
first influenza virus isolates have also been reported from
sporadic
cases in New York City; type A(H3N2) viruses have been isolated
from
residents of Brooklyn and the Bronx.
Tallies of patients** with influenza-like illnesses seen by
sentinel physicians nationwide increased from an average of 6.1 for
the reporting week ending January 1, 1986, to an average of 8.4 for
the week ending January 8. Similar increases have been observed in
recent seasons concurrently with the spread of influenza outbreaks.
The percentages of deaths from the 121 cities that were
associated
with pneumonia and influenza were 5.7% and 6.0% for the weeks
ending
January 11 and January 18, compared with the range of 4.9%-5.4% for
the 4 preceding weeks.
Reported by State and Territorial Epidemiologists; State Laboratory
Directors; W Owings, MD, Centreville, Alabama; D Pates, MD, Rupert,
Idaho; J Clark, M Earling, MD, Sunrise Hospital, R Weisner, MD, Las
Vegas, Nevada; K Bromberg, MD, Kings County Hospital, I Spigland,
MD,
Montefiore Hospital, New York City, S Lipson, PhD, K Szabo, MD,
Virus
Laboratory, Naussau County, New York; participating physicians of
the
American Academy of Family Physicians; 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: The antiviral drug, amantadine hydrochloride, is
highly effective in preventing illness caused by influenza type A
viruses and has been recommended by the Immunization Practices
Advisory Committee (ACIP) as an adjunct to vaccination in the
control
of influenza A infections (2). Amantadine is not effective against
influenza type B viruses or other respiratory pathogens. Although
amantadine seldom causes serious side effects in healthy, younger
adults, it is more likely to cause troublesome side effects in
older
persons. When the normal adult dose of 200 mg daily has been
reduced
to 100 mg in individuals 65 years of age or older, as recommended
by
the ACIP, the incidence and severity of side effects has decreased
substantially; however, particularly for older individuals, it is
undesirable to administer amantadine over the several weeks
required
to prevent possible spread or reintroduction of influenza A viruses
once the first evidence for an outbreak is detected, if the
outbreak
is actually due to influenza B or another respiratory pathogen.
The ability to rapidly diagnose influenza A infections would
provide greater confidence in the use of amantadine for early
treatment and prophylaxis of such cases, particularly when both
type A
and B influenza viruses are circulating. Nasopharyngeal specimens
properly collected from residents and/or staff members within the
first 1-3 days of illness before administration of amantadine can
be
tested using fluorescent microscopy and recently developed
monclonal
antibody reagents (3,4) to determine within 1 day whether or not
influenza type A viruses are responsible for the outbreak. An
alternative strategy would be to administer amantadine for 3 days
to
high-risk patients of an institution when an outbreak is beginning,
and at the same time, obtain rapid virus culture confirmation by
detecting antigen synthesized within 72 hours of inoculation of
cell
culture (5). In such a case, amantadine could be discontinued if
either the outbreak continued to spread to amantadine-treated
individuals and/or the laboratory diagnosis identified influenza B
rather than influenza A viruses. Confirmation of influenza A
infection would justify continued use of amantadine until risk of
infection was over. Influenza A- and B-specific reagents for
rapid
virus typing have been distributed by CDC to all state health
departments and other collaborating laboratories before the
influenza
season, although not all such laboratories may have established the
diagnostic procedures referred to above.
References
CDC. Update: influenza activity--United States, worldwide.
MMWR
1986;35:28-9.
ACIP. Prevention and control of influenza. MMWR
1985;34:261-8,
273-5.
Gardner PS, McQuillin J. Rapid virus diagnosis. Application
of
immunfluorescence. 2nd ed. London: Butterworth & Co., 1980.
McQuillin J, Madeley CR, Kendal AP. Monoclonal antibodies for
the
rapid diagnosis of influenza A and B virus infections by
immunofluorescence. Lancet 1985;II:911-4.
Walls HH, Harmon MW, Slagle JJ, et al. Characterization and
evaluation of monoclonal antibodies developed for typing
influenza
A and influenza B viruses. J Clin Micro 1986 (in press).
*Fever of 37.7 C (100 F) or higher and one or more respiratory
symptoms. Approximately 20% of the 100 staff also had febrile
respiratory illnesses slightly before or during the outbreak among
residents.
**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. Page converted: 08/05/98
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