RSV activity common outside of RSV "season"

By Megan Rauscher

NEW YORK (Reuters Health) - Respiratory syncytial virus (RSV) activity is widespread in the United States prior to November 1st, which has traditionally been accepted as the start of RSV season, according to results of a study presented this week at the American Academy of Pediatrics national meeting in Boston.

RSV is a common virus that most children get by the time they are two years old. It is the leading cause of hospital admissions in young children, causing breathlessness and wheezing and in some cases pneumonia.

Traditionally, infection with RSV occurs between November and March, yet there is growing evidence that RSV outbreaks vary by geographic region and from year to year, Dr. Aleta B. Bonner from Dell Children's Medical Center of Central Texas in Austin noted in an interview with Reuters Health.

Bonner's team analyzed RSV activity in September and October over two consecutive years (2006 and 2007) using data recorded in 31 hospital emergency departments in 21 states.

A total of 1,420 infants younger than 1 year of age were studied and had specimens tested for RSV.

"We found that there was a significant amount of RSV that was circulating in different geographic regions of the United States in both September and October of 2006 and 2007," Bonner said.

In the Northeast and Southeast, widespread RSV activity was seen in both September and October of both years, while in the Midwest, widespread activity was seen in October of 2006 and October of 2007.

In the South Central region, RSV activity was widespread in September of 2006 and October of 2006 and 2007. In the Northwest, RSV activity was widespread in September and October of 2007. The Southwest was the only region without widespread RSV activity in September and October of 2006 and 2007.

"The messages here are twofold," Bonner said. "One is that RSV is definitely out there in months other than we traditionally think, and two, RSV displays a fairly significant geographic pattern; we always think of it as starting more on the east coast and swinging to the west coast and we saw that in both years of the study."