Around midnight each night, the medical records of everyone who has visited an emergency room in Westchester County during the previous 24 hours are dumped into a central computer. For the next few hours the records, with names deleted to protect privacy, are electronically sorted according to symptoms — stomach pains, trouble breathing, fever. The computer scours them to detect a spike in cases. Employees at the county Health Department then check on anything unusual, calling the emergency rooms for an explanation, say, of high numbers of patients with chest pain. This early warning system is designed to catch an outbreak, be it the flu or a bioterrorism attack that is sickening residents. Full Story