an acute highly contagious, respiratory disease caused primarily by a Type-A influenza virus and characterised by depression, fever, anorexia, coughing, dyspnea, muscular weakness, prostration, and a mucous discharge from the eyes and nose. Pigs are the principal hosts of swine influenza virus, although influenza viruses found in pigs also occur in man and birds, harva esinev inimestele ja sigadele nakkav A-viiruse alatüüp, tõenäoliselt sama, nagu 1918.-1919.a. haiguse tekitaja