ATLANTA - Although respiratory syncytial virus (RSV) affects infants between the ages of 2 and 6 months most severely and infects most children by age 2, the disease should not be ruled out for older children and adults, especially during the winter months.
Because protective immunity is limited, RSV should be suspected when older children and adults present with acute respiratory disease during a community outbreak. RSV can cause severe complications in people with underlying cardiac or pulmonary disease or in immunocompromised patients and the elderly, as well as in young children. RSV infection among bone marrow transplant recipients has resulted in mortality rates as high as 83%. About 30 per 1,000 children are hospitalized with RSV during the first year of life, according to David Shay, MD, medical epidemiologist in the respiratory and enteric viruses branch at the Centers for Disease Control and Prevention. Currently, RSV is believed to cause between 200 and 500 deaths per year among young children.
And if the disease is following trends of past years, the United States is probably in the middle of the 2000-2001 peak season for RSV. Surveillance data recently published in the Morbidity and Mortality Weekly Report indicate that widespread activity occurred from late October 1999 through late March 2000 during the 1999-2000 RSV season.
From July 1999 though June 2000, 72 laboratories in 45 states reported 123,769 tests for RSV. Fifteen percent of tests (18,981) were positive. Widespread activity occurred during the week of Oct. 30, 1999, and continued for 26 weeks, until the week of March 25, 2000. Dates of onset ranged from Sept. 18, 1999, to Jan. 29, 2000, and dates of conclusion ranged from Jan. 29 to May 6. Regional outbreaks occurred earliest in the South (approximately Oct. 16, 1999, to March11, 2000), later in the Northeast (approximately Nov. 27, 1999, to April 15, 2000) and latest in the Midwest (approximately Dec. 28, 1999, to April 1, 2000) and West (approximately Nov. 13, 1999, to April 8, 2000).
For activity to be considered widespread, >50% of participating laboratories had to report one or more RSV detections for at least two consecutive weeks, and >10% of specimens tested for RSV during a surveillance week had to be positive.
Although most cases (92%) were reported from Oct. 30, 1999, through March 25, 2000, isolated cases of RSV were reported throughout the year. For example, isolates were reported from laboratories in California, Colorado, Hawaii, Louisiana, Texas, Virginia and Washington in July and August 1999.
Average months of peak activity and regional trends during the 1999-2000 surveillance season were similar to trends observed in previous years. The RSV season's duration was also similar, including the earlier onset of RSV outbreaks in southern states.
For more information:
- CDC. Respiratory syncytial virus activity United States, 1999-2000 Season. MMWR 2000;49(48):1091-1093.
- Shay DK, Holman RC, Newman RD, et al. Bronchiolitis-associated hospitalizations among U.S. children, 1980-1996. JAMA. 999;282:1440-46.
- Shay DK, Holman RC, Roosevelt GE, et al. Bronchiolitis-associated mortality and estimates of respiratory syncytial virus-associated deaths among U.S. children, 1979-1997. J Infect Dis. 2001;183:16-22.
You can express your views on this article, or other relevant themes, in the Infectious Diseases in Children Specialty Forums.