What is swine flu?
Like people, pigs can get influenza (flu), but swine flu viruses 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 — and it’s happening among people who haven’t had any contact with pigs. That makes it a human flu virus. To distinguish it both from flu viruses that infect mainly pigs and from the seasonal influenza A H1N1 viruses that have been in circulation for many years, the CDC calls the virus “novel influenza A (H1N1) virus” and the World Health Organization calls it “pandemic (H1N1) 2009.” The CDC calls swine flu illness “H1N1 flu” and the World Health Organization calls it “pandemic influenza A (H1N1).
