Lead: "'Episims' unleashes virtual plagues in real cities to see how social networks spread disease. That knowledge might help stop epidemic." This aritlce describes the Episims project of the Los Alamos National Laboratory. (http://www.ccs.lanl.gov/ccs5/) Episims is an individual-based epidemic model on a scale of millions of people implemented using high-performance supercomputing clusters (and building on an existing model called TRANSIMS developed over more than a decade at Los Alamos for urban planning), "Recently, as part of a research network organized by the National Institute of General Medical Sciences called the Models of Infectious Disease Agent Study (MIDAS), we have been adapting EpiSims to model a naturally occurring disease that may threaten the entire planet: pandemic influenza." By Chris L. Barrett, Stephen G. Eubank and James P. Smith, Scientific American, March 2005. (HTML, 5 pages.)