Pandemic (H1N1) 2009
Timeline
A small number of Pandemic (H1N1) 2009 cases were first reported by the government of the United States of America in mid-late April 2009. At the same time, the Mexican government reported three separate incidents of influenza-like-illness (ILI) throughout the country. Subsequent investigation found that a dozen cases had tested positive for the same virus as in California and Texas.
For a comprehensive timeline of the virus' transmission, click here