The Long Journey to Resolve the Origins of a Previous Pandemic

Dozens of researchers, including myself, worked for years to uncover that swine flu had leapt to humans from a pig in Mexico in 2009. We learned a lot about influenza evolution, pig farming, and outbreak risk along the way.

Written byMartha Nelson
| 15 min read
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ABOVE: Farmed swine are routinely inspected by veterinarians, who often take samples for viral testing and, occasionally, sequencing.
© ISTOCK.COM, RAT0007

It was the spring of 2009; US President Barack Obama was just settling into the White House when the Centers for Disease Control and Prevention (CDC) informed him that a new influenza A virus had suddenly appeared in kids in Southern California and was likely to spread around the world. The global pandemic that scientists feared had finally arrived, only no one predicted it would come from North America.

National security advisors and public health officials had been warning the White House for years that dangerous flu viruses were circulating in birds that were only a handful of mutations away from jumping to humans, potentially sparking a pandemic like the notorious 1918 influenza outbreak that claimed more than 20 million lives globally. But US health officials expected the next globe-trotting ...

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Meet the Author

  • Martha Nelson, an evolutionary biologist in the Intramural Research Program at the US National Institute of Allergy and Infectious Diseases

    Martha Nelson is an evolutionary biologist in the Intramural Research Program at the US National Institute of Allergy and Infectious Diseases. 

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