1 figure omitted
Respiratory syncytial virus (RSV) is a major cause of lower respiratory
tract infections (LRTIs) (i.e., bronchiolitis and pneumonia) among young children,
resulting in an estimated 51,000-82,000 hospitalizations annually.1 RSV
causes severe disease among older adults and persons of all ages with compromised
respiratory, cardiac, or immune systems, and can exacerbate chronic cardiac
and pulmonary conditions.1,2 3,4 In temperate climates, RSV infections
occur primarily during annual winter season outbreaks. This report summarizes
trends in RSV activity reported to the National Respiratory and Enteric Virus
Surveillance System (NREVSS) during July 2003–June 2004 and presents
preliminary data from the weeks ending July 3–December 4, 2004, indicating
the onset of the 2004-05 RSV season. Health-care providers should consider
RSV in the differential diagnosis for persons of all ages with LRTIs, implement
appropriate isolation precautions to prevent nosocomial transmission,5 and provide appropriate immune prophylaxis to eligible children, including
certain premature infants or children and infants with chronic lung and heart
NREVSS is a voluntary, laboratory-based surveillance system of 87 clinical
and public health laboratories in 40 states and the District of Columbia.
The laboratories report weekly to CDC the number of specimens tested and number
positive for several respiratory and enteric viruses by antigen detection
and virus isolation methods. During July 2003–June 2004, of 172,247
tests for RSV reported, 21,236 (12%) were positive.
Widespread RSV activity* began the week ending November 1, 2003, and
continued for 22 weeks until April 3, 2004. Activity peaked during February
for all regions†. Regional RSV activity occurred earliest in the South
(35 sites reporting; median weeks of onset and conclusion: November 1, 2003,
and March 27, 2004, respectively), later in the Northeast (seven sites; December
6, 2003, and March 27, 2004) and the Midwest (20 sites; December 6, 2003,
and March 27, 2004), and latest in the West (16 sites; December 27, 2003,
and April 3, 2004).
Although 93% of RSV detections were reported from the weeks ending November
1, 2003–April 3, 2004, sporadic detections were reported throughout
the year. During May-October 2004, laboratories in 33 states with at least
one laboratory per region reported RSV detections.
For the current reporting period (July 3–December 4, 2004), 84
laboratories in 42 states reported testing for RSV. Since November 6, a total
of 50 participating laboratories have reported RSV detections. Preliminary
2004-05 data suggest that the annual outbreak has begun in two regions—in
the South during the week ending October 30 and in the Northeast during the
week ending November 27 (Figure).
Because RSV infection only confers partial protection from subsequent
infection, reinfections occur throughout life.3,4 As a result,
health-care providers should consider RSV as a cause of acute respiratory
disease in all age groups during community outbreaks, particularly in young
children. Rapid diagnostic techniques for clinical use vary in sensitivity
and specificity. Certain assays are sensitive for diagnosis in infants and
young children, but few are sensitive for diagnosis in older children and
adults. Polymerase chain reaction–based assays with enhanced product
detection systems can be sufficiently sensitive to detect most infections
in all age groups.7, 8 Accurate diagnosis of RSV infection is crucial
for appropriate infection control, to rule out cocirculating viruses (e.g.,
influenza viruses) and to avoid inappropriate use of antimicrobial agents.
Infants and children at risk for serious RSV infection should receive monthly
doses of humanized murine anti-RSV monoclonal antibody throughout the RSV
season.6 Infants and children at risk include those aged <24
months with chronic lung disease who have required medical therapy (e.g.,
supplemental oxygen, bronchodilator, diuretic, or corticosteroid therapy)
within 6 months of RSV season onset and those with hemodynamically significant
heart disease, and preterm infants born at <32 weeks’ gestation or
preterm infants born at 32-35 weeks’ gestation with at least two additional
risk factors (e.g., child care attendance, exposure to environmental pollutants,
school-aged siblings, congenital abnormalities of the airways, or neuromuscular
disease) during their first RSV season. Because the onset of RSV activity
can vary between regions and communities, physicians and health-care facilities
should consult their local clinical laboratories for the latest data on RSV
Additional information and updates on RSV trends are available at http://www.cdc.gov/ncidod/dvrd/revb/nrevss/index.htm.
National Respiratory and Enteric Virus Surveillance System collaborating
laboratories. KJ Felton, I Pandya-Smith, MPH, AG Curns, MPH, AM Fry, MD, LJ
Anderson, MD, Div of Viral and Rickettsial Diseases, National Center for Infectious
Diseases; NM Keeler, DVM, EIS Officer, CDC.
REFERENCES: 10 available
*Widespread RSV activity is defined by NREVSS as the first of 2 consecutive
weeks, when 50% of participating laboratories report RSV detections or isolations
and when a mean percentage of specimens positive by antigen detection is >10%.
†Northeast: Connecticut, Maine, Massachusetts,
New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont; Midwest: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota,
Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin; South: Alabama, Arkansas, Delaware, District of Columbia,
Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina,
Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia; West: Alaska, Arizona, California, Colorado, Hawaii, Idaho,
Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.
Brief Report: Respiratory Syncytial Virus Activity—United States, 2003-2004. JAMA. 2005;293(10):1186. doi:10.1001/jama.293.10.1186