Wisconsin’s bout with avian influenza came amid an epidemic that would eventually become the worst in U.S. history. In just a few weeks over April and May 2015, nine commercial farms and one backyard flock in the state fell prey to the virus, leading to the establishment of four quarantine zones and the mass euthanasia, or depopulation, of 1.9 million birds. The epidemic was particularly hard on the Upper Midwest’s commercial poultry industry, with Iowa and Minnesota suffering far greater losses than Wisconsin.

This interactive timeline puts Wisconsin’s avian-flu cases in the context of the broader outbreak— be sure to consult the embedded videos and links for even more background on how the epidemic affected the state and the nation.

Learn more in a comprehensive overview about the avian influenza epidemic in Wisconsin.