In March 2009, a number of cases of an influenza-like illness and severe respiratory infections in humans were reported in parts of Mexico. These cases were later confirmed to be a strain of influenza A(H1N1), commonly referred to as swine flu and later called 2009 H1N1. By the end of April 2009, confirmed human cases of 2009 H1N1 infection were reported throughout Mexico, in parts of the United States, and in several countries worldwide. Reports of the outbreakcoupled with the use of the initial moniker swine fluinitially caused a downturn in domestic and international pork markets.