Now that historical and epidemiological forces are making the world smaller and causing lines between medicine and public health to blur, systems will need to be multifunctional, and clinical and public health systems will, of necessity,coalesce. Public health systems need to inform the state of the health ecology. To fill that need, public health and clinical informaticians will need to work closely together to build the tools to study and control new and emerging infectious diseases,bioterrorism threats, and support efforts to respond to and manage natural disasters and other environmental effects on health (see photo in Fig. 16.2 ).For example, in the late 1990’s, Columbia Presbyterian Medical Center and the New York City Department of Health collaborated on the development of a tuberculosis registry for northernManhattan, and the Emory University System of Health Care and the Georgia Department of PublicHealth built a similar system for tuberculosis monitoring and treatment in Atlanta. It is not by chance that these two cities each developed tuberculosis systems; rather, tuberculosis is a perfect example of what was once a public health problem (that affected primarily the poor and underserved) coming into the mainstream population as a result of an emerging infectious disease (AIDS), immigration,