ABSTRACT
Effective surveillance warns of threats and allows the adaptation of public health programming to meet an evolving concern or the initiation of public health programming to address a novel threat. Disease surveillance programming based upon monitored indicators and event-based surveillance usually is predicated on the search for an acute change above noise in the detection system. Event-based surveillance also could evolve toward considering risk for disease to a greater extent rather than only presence of disease. Several challenges exist to constructing and using cross-border surveillance. The International Health Regulations takes a regulatory step toward a holistic view of what impacts public health and the kinds of cooperative relationships that should exist between affected and at-risk countries. The World Health Organization secretariat has the challenging task of helping countries navigate their varied risks when public health events arise as well as both alerting and leveraging the global community, when appropriate.
