Where did the h. one n. one virus originate?
The swine-origin influenza A (H1N1) virus that appeared in 2009, was first found in human beings in Mexico.
H1N1 is a human respiratory infection caused by an influenza strain that originated in pigs. Swine flu was first recognized in the 1919 pandemic and still circulates as a seasonal flu virus. The swine flu pandemic of 2009 began with one case in Mexico and 2 cases in southern California.
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