Active Surveillance for Influenza A Virus among Swine, Midwestern United States, 2009–2011
Cesar A. Corzo, Marie Culhane , Kevin Juleen, Evelyn Stigger-Rosser, Mariette F. Ducatez, Richard J. Webby, and James F. Lowe
Author affiliations: University of Minnesota, Saint Paul, Minnesota, USA (C.A. Corzo, M. Culhane, K. Juleen); St. Jude Children’s Research Hospital, Memphis, Tennessee, USA (E. Stigger-Rosser, M.F. Ducatez, R.J. Webby); Carthage Veterinary Services, Carthage, Illinois, USA (J.F. Lowe)
Figure 1. . Swine influenza virus group status for 32 pig farms participating in an active surveillance project, midwestern United States, June 2009–December 2011. Each horizontal line represents a farm, each dot represents a sampling event, and colors indicate virus status of the group.
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