Rotavirus is one of the leading causes of severe diarrhea in infants. It is estimated to cause over half a million deaths worldwide each year. In the United States, rotavirus leads to approximately 60,000 hospitalizations and 30-40 deaths annually, most of which are in children under 5 years of age.
Epidemics of rotavirus in the U.S. traditionally begin in the southwest in December and peak approximately 3 months later in the northeast. Explaining this epidemic pattern has been difficult, as the timing of epidemics is not associated with any climatic indicators such as temperature, solar radiation or precipitation, which have typically been thought to dictate seasonal patterns of infectious diseases.
A team of researchers, led by Virginia Pitzer and Bryan Grenfell, has shed light on the previously unexplained epidemic pattern of this virus using a mathematical model that incorporates data on birth rates and rotavirus epidemiology. They show that regional variation in birth rates can explain the differences in the timing of epidemics across the U.S. In other words, the annual onset of rotavirus epidemics is delayed in areas with decreased birth rates, which generally occurs in the northeast. Additionally, these researchers were able to retrospectively predict the response to rotavirus vaccination, in which a small decrease in the incidence of severe diarrhea occurred during the 2006-2007 season, followed by a large decline and delay in 2007-2008, providing important validation of their model. This research shows that the impact of vaccination against rotavirus extends beyond those who receive the vaccine, as vaccination lowers the overall prevalence of the infection and thereby indirectly protects unvaccinated individuals. Thus, vaccination can lead to changes in the pattern of infection and epidemics in the population as a whole.
Synopsis written by Anne Buboltz
Written By: Pitzer, VE, Viboud, C, Simonsen, L, Steiner, C, Panozzo, CA, Alonso, WJ, Miller, MA, Glass, RI, Glasser, JW, Parashar, UD, & Grenfell, BT
Journal: 325: 290-294
Journal Reference: 325: 290-294
Paper Id: 10.1126/science.1172330