Science
10 July 2009  Vol 325, Issue 5937, Pages 117-232
http://www.sciencemag.org/current.dtl

Perspectives
Epidemiology:
Does Viral Diversity Matter?

Graham F. Medley1 and D. James Nokes1,2

Epidemic viruses, such as severe acute respiratory syndrome (SARS) and influenza A, cause diseases that rapidly spread to many people, and seem to attract more scientific and public attention than do endemic viruses, which are continually present in populations. Yet endemic viruses cause far greater disability and death. But epidemic viruses are endemic somewhere, or will become so, and endemic viruses are often recurrently epidemic. So developing a full understanding of the mechanisms that promote and drive endemicity is key to reducing the overall burden of viral disease and reducing the risk of future, widespread pandemics. On page 290 of this issue, Pitzer et al. (1) investigate the causes of epidemics of rotavirus, a major, global endemic virus.

1 Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
2 Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.