News Release

NIH-supported study pinpoints origin of 2009 H1N1 influenza pandemic

Peer-Reviewed Publication

NIH/National Institute of Allergy and Infectious Diseases


Researchers have used genetic sequencing to show that the 2009 global H1N1 influenza pandemic began in central Mexico, originating in pigs and spreading to humans. Mexico is not typically considered a source of novel influenza strains. The new findings appear online in the journal eLIFE. They shed light on how the novel virus evolved and stress the need for improved influenza surveillance. The research was supported by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health,

The U.S. Centers for Disease Control and Prevention estimates that nearly 300,000 people died worldwide during the 2009-2010 flu season as the result of pandemic H1N1 infection. The pandemic H1N1 influenza virus that emerged that season was not previously known to infect people and is unrelated to the human seasonal H1N1 viruses that have circulated since 1977. Its global spread caused severe illness and death patterns not normally seen in seasonal influenza infections. The new study suggests that the first human outbreak of pandemic H1N1 occurred in Mexico in early 2009; no other related swine influenza viruses had been detected in Mexico or any part of the Americas.

The new research suggests the need to track the geographical distribution of influenza type A viruses, including H1N1, in global swine populations. Future influenza pandemic preparedness will require improved viral surveillance and an understanding of how economic forces and international trade policies affect changes in animal movements and production practices that contribute to viral outbreaks, the authors write.


I Mena, M Nelson, F Quezada-Monroy et al. Origins of the 2009 H1N1 influenza pandemic in swine in Mexico. eLIFE DOI: 10.7554/eLife.16777 (2016).


NIAID Director Anthony S. Fauci, M.D.; David Spiro, Ph.D., chief, Influenza, SARS, and Related Viral Respiratory Diseases Section, in NIAID's Division of Microbiology and Infectious Diseases; and Martha Nelson, Ph.D., research fellow, Fogarty International Center, are available for comment.



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