Human infections with swine influenza have been detected occasionally since the late 1950s usually in persons with direct exposure to pigs (e.g. people working in pig farms, etc.).
Inimeste nakatumist seagrippi on 1950. lõpust alates aeg-ajalt diagnoositud inimestel, kellel on vahetu kokkupuude sigadega (nt seatalitajad).