Active influenza surveillance at the local level: a model for local health agencies.

Laboratory-supported, community-based local surveillance systems for influenza can act as early warning systems in identifying the initial entry points of different influenza strains into the community. Unfortunately, local health departments often have limited resources to implement this type of surveillance. We developed and evaluated an active, local influenza surveillance system in 3 metropolitan Denver, Colo, counties that enabled timely case ascertainment and strain identification at little cost. When compared with Colorado's surveillance system, our system detected cases 7 to 8 weeks earlier than the state's electronic disease reporting system.