Fig. 2.

Structure of surveillance for influenza A virus (IAV) in swine. The foundation of a surveillance system is diagnostic screening for presence of IAV. At each level, the number of samples to test are reduced by screening and analyses to identify IAV of interest, but the level of complexity for each subsequent stage increases, allowing for fewer specialized entities to contribute. The ultimate goals of an integrated and collaborative IAV surveillance network are to monitor and report genetic and antigenic evolution to inform animal and public health sectors, update diagnostics and vaccines as needed, identify relevant strains for further research, and to develop and implement improved intervention strategies.