Predicting the Unpredictable

The ability to predict the course of a disease epidemic is immensely valuable. In his Perspective, [Medley][1] dwells on the pros and cons of predicting the outcome of the variant Creutzfeld-Jakob disease epidemic in humans ([ Huillard d'Aignaux et al .][2], [ Valleron et al .][3]) and the bovine spongiform encephalopathy epidemic in sheep (Kao et al .) in the United Kingdom. He suggests that the value of disease predictions lies not in the numerical values, but in the insights gleaned about the processes underlying the initiation and progression of epidemics. [1]: http://www.sciencemag.org/cgi/content/full/294/5547/1663 [2]: http://www.sciencemag.org/cgi/content/short/294/5547/1729 [3]: http://www.sciencemag.org/cgi/content/short/294/5547/1726