"Significant variability" in RSV outbreaks, says study

There is significant variability in the onset and duration of respiratory syncytial virus activity between US metropolitan areas  located within the same region, according to a report published in the  Pediatric Infectious Disease Journal by biotechnology company MedImmune  and the disease surveillance and health care informatics organization  SDI.

For example, in the three-year study using MedImmune's surveillance  program, RSV Alert, greater than 73% of all the measured areas revealed  at least one week of significant RSV activity outside the traditional  American Academy of Pediatrics-defined season for disease activity in  their region, which is typically November through March. In addition,  the study found that the southern region experienced the longest  duration and earliest conclusion of RSV activity, while the Midwest  region exhibited the latest season commencement and peak. The report  also noted that portions of Florida demonstrated year-round RSV  outbreaks.

Furthermore, Las Vegas, Portland and Salt Lake City had longer RSV  seasons than other areas in the region. Investigators hypothesized that  the expanded season could be due to the large influx of visitors from  international tourism and business conventions during peak travel  months. Additionally, Ohio, Illinois and Missouri had metropolitan areas  that experienced an RSV season that was at least four weeks longer than  the average for the region.