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Seasonal respiratory syncytial virus (RSV) epidemics occur annually in temperate climates and result in significant pediatric morbidity and increased healthcare costs. Although RSV epidemics generally occur between October and April, the size and timing vary across epidemic seasons and are difficult to predict accurately. Prediction of epidemic characteristics would support management of resources and treatment.
Molly Leecaster, of the Division of Epidemiology at the University of Utah School of Medicine in Salt Lake City, and colelagues, sought to examine the empirical relationships among early exponential growth rate, total epidemic size, and timing, and the utility of specific parameters in compartmental models of transmission in accounting for variation among seasonal RSV epidemic curves. RSV testing data from Primary Children's Medical Center were collected on children from July 2001 to June 2008. Simple linear regression was used to explore the relationship between three epidemic characteristics (final epidemic size, days to peak, and epidemic length) and exponential growth calculated from four weeks of daily case data. A compartmental model of transmission was fit to the data and parameter estimates were used to help describe the variation among seasonal RSV epidemic curves.
The researchers repiort that the regression results indicated that exponential growth was correlated to epidemic characteristics. The transmission modeling results indicated that start time for the epidemic and the transmission parameter co-varied with the epidemic season.
Leecaster, et al. concluded that exponential growth was somewhat empirically related to seasonal epidemic characteristics and that variation in epidemic start date as well as the transmission parameter over epidemic years could explain variation in seasonal epidemic size. They say these relationships are useful for public health, healthcare providers and infectious disease researchers. Their research was published in BMC Infectious Diseases.
Reference: Leecaster M, Gesteland P, Greene T, Walton N, Gundlapalli A, Rolfs R, Byington C and Samore M. Modeling the variations in pediatric respiratory syncytial virus seasonal epidemics. BMC Infectious Diseases 2011, 11:105doi:10.1186/1471-2334-11-105