As always for a presidential inaugural, security and surveillance were extremely tight in Washington, DC, last January. But as George W. Bush prepared to take the oath of office, security planners installed an extra layer of protection: a prototype software system to detect a biological attack. The U.S. Department of Defense, together with regional health and emergency-planning agencies, distributed a special patient-query sheet to military clinics, civilian hospitals and even aid stations along the parade route and at the inaugural balls. Software quickly analyzed complaints of seven key symptoms-from rashes to sore throats-for patterns that might indicate the early stages of a bio-attack. There was a brief scare: the system noticed a surge in flulike symptoms at military clinics. Thankfully, tests confirmed it was just that-the flu.

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