3Scatozza F,Sidoli L.Effects of Haemophilus pleuropneumonia infection in piglets recovering from influenza[J].Proc Int Pig Vet Soc,1986,9:150.
4Pol J M,Van Leengoed L A,Stockhofe N,et al.Dual infections of PRRSV/influenza or PRRSV/Actinobacillus pleurop-neumoniae in the respiratory tract[J].Vet Microbiol,1997,55:259-264.