Swine Flu

Swine flu is common in pigs, and rare in humans. People who work with swine are at risk of catching swine influenza if the swine carry a strain able to infect humans. However, these strains rarely are able to pass from human to human. Rarely, SIV mutates into a form able to pass easily from human to human. The strain responsible for the 2009 H1N1 "swine flu" outbreak is believed to have undergone such a mutation.  For information on the 2009 H1N1 "Swine Flu" Pandemic, click here...

NOTE: This page contains background information about influenza in pigs. This page does NOT contain information about Pandemic 2009 H1N1  influenza (initially referred to as "swine flu" when it was first detected) that is spreading from person to person around the world.  For information about 2009 H1N1 flu, visit the Pandemic (H1N1) 2009 Influenza  information page here at www.MarinFlu.org.

Influenza A viruses are found in many different animals, including ducks, chickens, pigs, whales, horses and seals. Pigs can be infected with both human and avian influenza viruses in addition to swine influenza viruses. Infected pigs get symptoms similar to humans, such as cough, fever and runny nose. Because pigs are susceptible to avian, human and swine influenza viruses, they potentially may be infected with influenza viruses from different species (e.g., ducks and humans) at the same time. If this happens, it is possible for the genes of these viruses to mix and create a new virus. This type of major change in the influenza A viruses is known as antigenic shift. Antigenic shift results when a new influenza A subtype to which most people have little or no immune protection infects humans. If this new virus causes illness in people and can be transmitted easily from person to person, an influenza pandemic can occur.

Related Links

• Key Facts about Influenza in Pigs (CDC)This document provides interim guidance for state and local health departments conducting investigations of human cases of swine influenza A (H1N1) virus.
• Interim Guidance for People who have Close Contact with Pigs in Non-commercial Settings (CDC)