Design and operation of state and local infectious disease surveillance systems.

Since 2001, increased attention has been focused on improving acute infectious disease surveillance systems. This article describes options for their design and operation. Systems designed primarily to detect individual cases of reportable diseases may differ from those designed to detect outbreaks or support design or evaluation of control programs. Timeliness, sensitivity, and predictive value of surveillance systems cannot all be maximized at the same time. Core activities of surveillance systems include collection, analysis, and dissemination of information about health events under surveillance. Doing these well requires attention to the mechanics of surveillance, such as making the health department accessible at all times to receive reports and provide consultation, and maintaining current directories of persons for dissemination of surveillance data, alerts, and recommendations. Rapid access to electronic representations of health events (eg, laboratory reports, patient records, or health care claims) provides great opportunities for more timely and complete surveillance. Some important information (eg, exposures, contacts) will still need to be collected directly from affected persons. One productive strategy is to collect core demographic and onset data on all cases and detailed clinical, exposure, and outcome data on a subset.