Current Trends
Update: Respiratory Syncytial Virus Activity --
United States, 1994-95 Season
Respiratory syncytial virus (RSV), a common cause of winter
outbreaks of acute respiratory disease, causes an estimated 90,000
hospitalizations and 4500 deaths each year from lower respiratory
tract disease in both infants and young children in the United
States (1). Outbreaks occur annually throughout the United States,
and community activity usually peaks within 1 month of the national
peak (2). RSV activity in the United States is monitored by the
National Respiratory and Enteric Virus Surveillance System
(NREVSS), a voluntary, laboratory-based system. This report
presents provisional surveillance results from the NREVSS for RSV
during July 2-December 9, 1994, and summarizes trends in RSV from
July 1, 1990, through July 1, 1994.
Since July 1, 1990, a total of 105 hospital-based and public
health laboratories in 47 states have participated in the NREVSS
and have reported weekly to CDC the number of specimens tested for
RSV by the antigen detection and virus isolation methods and the
number of positive results. Widespread RSV activity is defined by
the NREVSS as the first of 2 consecutive weeks when at least half
of participating laboratories report any RSV detections. This
definition generally indicates a mean percentage of specimens
positive by antigen detection in excess of 10%. During the previous
four seasons, from July 1, 1990, through July 1, 1994, onset of
widespread RSV activity began in November and continued an average
of 24 weeks until April or mid-May Figure_1. The peak in
activity
occurred each year from mid-January through mid-February. For the
current reporting period (July 2-December 9, 1994), 85 laboratories
in 43 states reported results of testing for RSV. Since November
12, more than half of the participating laboratories reported
detections of RSV on a weekly basis, indicating the onset of RSV
activity for the 1994-95 season.
Reported by: National Respiratory and Enteric Virus Surveillance
System laboratories. Respiratory and Enteric Viruses Br, Div of
Viral and Rickettsial Diseases, National Center for Infectious
Diseases, CDC.
Editorial Note
Editorial Note: During the RSV season, health-care providers should
consider RSV as a cause of acute respiratory disease in both
children and adults. Most severe manifestations of infection with
RSV (e.g., pneumonia and bronchiolitis) occur in infants aged 2-6
months; however, children of any age with underlying cardiac or
pulmonary disease or who are immunocompromised are at risk for
serious complications from this infection. Because natural
infection with RSV provides limited protective immunity, RSV may
cause repeated symptomatic infections throughout life. In adults,
RSV usually causes upper respiratory tract manifestations but may
cause lower respiratory tract disease -- especially in the elderly
and in immunocompromised persons. Outbreaks among immunocompromised
persons can result in high death rates.
RSV is a common, but preventable, cause of nosocomially
acquired infection; the risk for nosocomial transmission is
increased during community outbreaks. Sources for nosocomially
acquired infection include infected patients, staff, visitors, or
contaminated fomites. Nosocomial outbreaks or transmission of RSV
can be controlled with strict attention to contact-isolation
procedures (3). In addition, chemotherapy with ribavirin is
indicated for some patients (e.g., those at high risk for severe
complications or those who are seriously ill with this infection)
(4). Prophylaxis with intravenous RSV immunoglobulin for high-risk
patients is being evaluated (5). Vaccines for RSV are being
developed, and some are being evaluated in clinical trials;
however, none have been proven safe and efficacious (6).
References
Institute of Medicine. Appendix N: prospects for immunizing
against respiratory syncytial virus. In: New vaccine development:
establishing priorities -- Volume 1: diseases of importance in the
United States. Washington, DC: National Academy Press, 1985:397-
Gilchrist S, Torok TJ, Gary HE Jr, Alexander JP, Anderson LJ.
National surveillance for respiratory syncytial virus -- United
States, 1985-1990. J Infect Dis 1994;170:986-90.
Garner JS, Simmons BP. Guideline for isolation precautions in
hospitals. Infect Control 1983;4(suppl):245-325.
Committee on Infectious Diseases, American Academy of
Pediatrics. Use of ribavirin in the treatment of respiratory
syncytial virus. Pediatrics 1993;92:501-4.
Groothuis JR, Simoes EAF, Levin MJ, et al. Prophylactic
administration of respiratory syncytial virus immune globulin to
high-risk infants and young children. N Engl J Med 1993;329:1524-7.
Murphy BR, Hall SL, Kulkarni AB, et al. An update on approaches
to the development of respiratory syncytial virus (RSV) and
parainfluenza virus type 3 (PIV3) vaccines. Virus Research
1994;32:13-36.
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