this is a virus found in pigs that causes swine influenza. the swine flu (h1n1) virus is different from the human flu virus. there are many different strains of swine flu (h1n1) virus (e. g. h1n1 h3n2). h1n1 is the most common. usually a swine flu (h1n1) virus infects only pigs or in rare cases those around pigs. but a new type of swine flu (h1n1) virus has been spreading from person to person.
what is the swine flu (h1n1) virus?