Brief report: respiratory syncytial virus activity--United States, 2004-2005.

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections (LRTIs) (e.g., bronchiolitis and pneumonia) among young children, resulting in an estimated 51,000-82,000 hospitalizations annually in the United States. RSV also causes severe disease and death among older persons and persons of all ages with compromised respiratory, cardiac, or immune systems and can exacerbate chronic cardiac and pulmonary conditions. In temperate climates, most RSV infections occur during a distinct seasonal peak. This report presents preliminary data from RSV activity reported to the National Respiratory and Enteric Virus Surveillance System (NREVSS) for the weeks ending July 2 through December 3, 2005, indicating the onset of the 2005-06 RSV season, and summarizes trends during July 2004-June 2005. 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, and provide appropriate immune prophylaxis to eligible children, including certain premature infants or infants and children with chronic lung and heart disease.