Epidemiologic Notes and Reports Respiratory Syncytial
Virus -- Oklahoma
From November 1985 through the end of January 1986, an
unusually
large number of respiratory illnesses due to respiratory syncytial
virus (RSV) occurred in Oklahoma.
Oklahoma Children's Memorial Hospital (OCMH), a 239-bed
teaching
hospital, serves Oklahoma City and is a tertiary referral center
for
central and western Oklahoma. From November 1985 through January
1986, more bronchiolitis was diagnosed each month among patients
visiting the OCMH emergency room (ER) than in any month of the
previous two winters (Figure 2). While the median age of patients
during this 3-month epidemic season (5 months, range 18 days to 70
months) was similar to that seen in the previous 2 years, the sex
distribution (51% female) differed in that the usual predominance
of
males (59% for the November 1984-March 1985 season, 67% for the
January 1984-March 1984 season) was not seen. In December, the
peak
month of the outbreak, more than twice as many patients were
hospitalized for bronchiolitis than in any month during the
previous 5
years.
RSV was identified in 66 (53.2%) of 124 nasopharyngeal
aspirates
submitted from hospitalized patients in December for viral culture
or
fluorescent antibody tests. This was the largest number of
positive
tests and the highest rate of RSV positivity for any month since
the
virology laboratory began testing for RSV in 1981. For patients
hospitalized at OCMH for bronchiolitis through December 10 of this
epidemic period, 39 (84.8%) of 46 of those who submitted
nasopharyngeal aspirates for testing had RSV infection.
Twenty-five
(67.6%) of 37 patients with pneumonia had RSV infection. Although
the
number of patients seen with RSV-related illness increased,
indicators
of the severity were similar to those seen in previous years. For
example, of 238 patients seen in the OCMH ER for bronchiolitis from
November 1, 1985, through January 31, 1986, 57 (23.9%) were
admitted
to the hospital, compared with 36 (16.7%) of 215 and 37 (24.2%) of
153
for the two previous seasons, respectively. Likewise, the rate of
admission to the intensive-care unit for patients with
laboratory-confirmed RSV illnesses was 8.8/100 ER visits for
bronchiolitis, compared with 8.4/100 for the previous season
(November
1984-March 1985). Two deaths at OCMH were attributed to RSV during
this season; one such death occurred during the previous year.
Reports of increased rates of bronchiolitis from physicians and
hospitals in areas of Oklahoma relative to previous years indicate
that the RSV epidemic is not limited to Oklahoma City.
Reported by W Pryor, MD, M Marks, MD, P Rettig, MD, J Waner, PhD, J
Steumky, MD, D Conrad, MD, J Christensen, MD, W Chapman, MD, S
Bullard, MD, J Hayes, MD, P Hines, MD, M Rock, MD, H Shalaby, PhD,
S
Todd, N Whitehurst, L Wall, Oklahoma Children's Memorial Hospital,
Oklahoma City, C Wood, J Dudly, Immunization Div, G Istre, MD,
State
Epidemiologist, Oklahoma State Dept of Health; Div of Field Svcs,
Epidemiology Program Office, Respiratory and Enterovirus Br, Div of
Viral Diseases, Center for Infectious Diseases, CDC.
Editorial Note
Editorial Note: RSV infection, the most common cause of
bronchiolitis
among infants, occurs in seasonal epidemics that usually peak in
the
winter months. For the last 10 years, data from seven to 16 U.S.
university virus laboratories show the average initial outbreak
month
(the first month with 8% or more of the year's total isolates) has
been December or January; the peak outbreak month, January or
February; and the duration of the outbreak, 2-4 months. Several
studies have shown that the number of RSV-associated illnesses
varies
from year to year (1,2). The Oklahoma outbreak, plus reports from
other (university) laboratories, suggest that the number of
RSV-associated illnesses has increased in several locations this
year. Data from these laboratories also suggest RSV activity
occurred
earlier than usual this season, with the average initial outbreak
month being November rather than December. The number of RSV
isolates
reported has increased through January in all reporting regions
except
the South Atlantic, where the number of RSV isolates peaked in
December.
RSV is the major cause of acute, lower respiratory illness
among
infants and young children worldwide. It is estimated that nearly
50%
of children under 1 year of age are infected with RSV during an
epidemic, and between one in 50 and one in 200 of these are
hospitalized (3). Among children hospitalized with RSV, mortality
rates between 0.5% and 5.6% have been reported (4-7), consistent
with
the two of 57 (3.5%) reported in this outbreak. Of particular
concern
during RSV outbreaks is the potential for nosocomial spread to
infants
and children at greatest risk for severe disease, such as those
with
compromised cardiac, pulmonary, or immune systems. A mortality
rate
as high as 37% has been reported among hospitalized children with
cardiac abnormalities who became infected with RSV (7). Nosocomial
RSV has also been associated with nearly a twofold increase in the
duration of hospitalization (8).
Recommendations for the control of RSV spread in hospitals
include
strict attention to good hand-washing practices and the use of
gowns
when contact with respiratory secretions of RSV-infected patients
is
likely. RSV-infected patients should be in private rooms or
cohorted
with other patients likely to be infected with RSV (9,10).
References
Glezen WP, Denny FW. Epidemiology of acute lower respiratory
disease in children. N Engl J Med 1973;288:498-505.
Kim HW, Arrobio JO, Brandt CD, et al. Epidemiology of
respiratory
syncytial virus infection in Washington, D.C. I. Importance
of
the virus in different respiratory tract disease syndromes and
temporal distribution of infection. Am J Epidemiol
1973;98:216-25.
Hall CB. Respiratory syncytial virus. In: Feigin RD, Cherry
JD,
eds. Textbook of pediatric infectious diseases. Vol. II.
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Eriksson M, Forsgren M, Sjoberg S, von Sydow M, Wolontis S.
Respiratory syncytial virus infection in young hospitalized
children. Identification of risk patients and prevention of
nosocomial spread by rapid diagnosis. Acta Pediatr Scand
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Clarke SKR, Gardner PS, Poole PM, Simpson H, Tobin JO.
Respiratory syncytial virus infection: admissions to hospital
in
industrial, urban, and rural areas. Report to the Medical
Research Council Subcommittee on Respiratory Syncytial Virus
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Gardner PS, Turk DC, Adherne WA, Bird T, Holdaway MD, Court
SDM.
Deaths associated with respiratory tract infection in
childhood.
Br Med J 1967;4:316-20.
MacDonald NE, Hall CB, Suffin SC, Alexson C, Harris PJ, Manning
JA. Respiratory syncytial viral infection in infants with
congenital heart disease. N Engl J Med 1982;307:397-400.
Hall CB, Douglas RG Jr, Geiman JM, Messner MK. Nosocomial
respiratory syncytial virus infections. N Engl J Med
1975;293:1343-6.
Garner JS, Simmons BP. Guideline for isolation precautions in
hospitals. Infect Control 1983;4(4 suppl):245-325.
Williams WW. Guideline for infection control in hospital
personnel. Infect Control 1983;4(4 suppl):326-49.
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