Update on public health surveillance in emergency departments.

The development of public health surveillance systems based on ED visits, in conjunction with other health and non-health-related data, is an important step to better understanding the health needs of the US population. There are multiple steps to develop a functional organization, and these actions require the support and involvement of many different partners. The ability to (1) analyze data; (2) distribute results; and (3) influence policy, funding, and patients' behavior are important outgrowths of these activities. This chapter discusses the opportunities and obstacles related to public health surveillance systems based on ED data.