Update: Respiratory Syncytial Virus Activity -- United States, 1995-96 Season

Respiratory syncytial virus (RSV), a common cause of winter outbreaks of acute respiratory disease, is associated each year with an estimated 90,000 hospitalizations and 4500 deaths 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 in January or February (Figure_1) (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 1-December 1, 1995, and summarizes trends in RSV from July 1990 through June 1995.

Since July 1, 1990, a total of 107 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 greater than 10%.

During the previous five seasons (i.e., July 1990-June 1995), onset of widespread RSV activity began in November and continued a mean of 22 weeks, until April or early May (Figure_1). Activity peaked each year from late January through mid-February. For the current reporting period (July 1-December 1, 1995), 72 laboratories in 44 states reported results of testing for RSV. Since October 21, more than half of the participating laboratories reported detections of RSV on a weekly basis, indicating the onset of RSV activity for the 1995-96 season.

Reported by: National Respiratory and Enteric Virus Surveillance System collaborating 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 in the differential diagnosis of acute respiratory disease in both children and adults. Most severe manifestations of RSV infection (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. In adults, RSV usually causes upper respiratory tract manifestations but may cause lower respiratory tract disease. Infection in immunocompromised persons can be associated with 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 may be indicated for some patients (e.g., those at high risk for severe complications or who are seriously ill with this infection) (4). Prophylaxis with intravenous RSV immunoglobulin for high-risk patients may become available during future RSV seasons (5), and vaccines for RSV are being developed (6).

References

1. 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- 409.

2. Gilchrist S, T½r½k 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.

3. CDC. Guideline for prevention of nosocomial pneumonia. Resp Care 1994;39:1191-236.

4. Committee on Infectious Diseases, American Academy of Pediatrics. Use of ribavirin in the treatment of respiratory syncytial virus. Pediatrics 1993;92:501-4.

5. 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- 30.

6. 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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