Swine influenza, also called
pig influenza,
swine flu,
hog flu and
pig flu, is an infection caused by any one of several types of swine influenza
viruses.
Swine influenza virus (
SIV) or
swine-origin influenza virus (
S-OIV) is any strain of the
influenza family of viruses that is
endemic in
pigs. As of 2009, the known SIV strains include
influenza C and the subtypes of
influenza A known as
H1N1,
H1N2, H2N1,
H3N1,
H3N2, and
H2N3.