H1N1 is a flu virus. When it was first detected in 2009, it was called swine flu
H1N1 is a flu virus. When it was first detected in 2009, it was called “swine flu” because the virus was similar to those found in pigs.
Swine flu, also known as 2009 H1N1 type A influenza, is a human disease. People get the disease from other people, not from pigs.
The disease originally was nicknamed swine flu because the virus that causes the disease originally jumped to humans from the live pigs in which it evolved. The virus is a "reassortant" -- a mix of genes from swine, bird, and human flu viruses. Scientists are still arguing about what the virus should be called, but most people know it as the H1N1 swine flu virus.
The swine flu viruses that usually spread among pigs aren't the same as human flu viruses. Swine flu doesn't often infect people, and the rare human cases that have occurred in the past have mainly affected people who had direct contact with pigs. But the current "swine flu" outbreak is different. It's caused by a new swine flu virus that has changed in ways that allow it to spread from person to person -- among people who haven't had any contact with pigs.
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