title: Serological patterns of Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae, Pasteurella multocida and Streptococcus suis in pig herds affected by pleuritis.
abstract: BACKGROUND
  Respiratory illness is traditionally regarded as the disease of the growing pig, and has historically mainly been associated to bacterial infections with focus on Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae. These bacteria still are of great importance, but continuously increasing herd sizes have complicated the scenario and the influence of secondary invaders may have been increased. The aim of this study was to evaluate the presence of A. pleuropneumoniae and M. hyopneumoniae, as well as that of the secondary invaders Pasteurella multocida and Streptococcus suis by serology in four pig herds (A-D) using age segregated rearing systems with high incidences of pleuritic lesions at slaughter.
  
  
  RESULTS
  Pleuritic lesions registered at slaughter ranged from 20.5 to 33.1 % in the four herds. In herd A, the levels of serum antibodies to A. pleuropneumoniae exceeded A450> 1.5, but not to any other microbe searched for. The seroconversion took place early during the fattening period. Similar levels of serum antibodies to A. pleuropneumoniae were also recorded in herd B, with a subsequent increase in levels of antibodies to P. multocida. Pigs seroconverted to both agents during the early phase of the fattening period. In herd C, pigs seroconverted to P. multocida during the early phase of the fattening period and thereafter to A. pleuropneumoniae. In herd D, the levels of antibodies to P. multocida exceeded A450> 1.0 in absence (A450< 0.5) of antibodies to A. pleuropneumoniae. The levels of serum antibodies to M. hyopneumoniae and to S. suis remained below A450< 1.0 in all four herds. Pigs seroconverted to M. hyopneumoniae late during the rearing period (herd B-D), or not at all (herd A).
  
  
  CONCLUSIONS
  Different serological patterns were found in the four herds with high levels of serum antibodies to A. pleuropneumoniae and P. multocida, either alone or in combination with each other. Seroconversion to M. hyopneumoniae late during the rearing period or not at all, confirmed the positive effect of age segregated rearing in preventing or delaying infections with M. hyopneumoniae. The results obtained highlight the necessity of diagnostic investigations to define the true disease pattern in herds with a high incidence of pleuritic lesions.
authors.affiliation: National Veterinary Institute, SVA, 751 89, Uppsala, Sweden. Per.Wallgren@sva.se.|Department of Clinical Sciences, Swedish University of Agricultural Sciences (SLU), Box 7054, 750 07, Uppsala, Sweden. Per.Wallgren@sva.se.
authors.forename: Per
authors.initials: P
authors.lastname: Wallgren
authors.affiliation: Farm & Animal Health, Kungsängens Gård, 753 23, Uppsala, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Nörregård
authors.affiliation: Farm & Animal Health, Kungsängens Gård, 753 23, Uppsala, Sweden.
authors.forename: Benedicta
authors.initials: B
authors.lastname: Molander
authors.affiliation: National Veterinary Institute, SVA, 751 89, Uppsala, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Persson
authors.affiliation: Farm & Animal Health, Kungsängens Gård, 753 23, Uppsala, Sweden.
authors.forename: Carl-Johan
authors.initials: CJ
authors.lastname: Ehlorsson
mesh_terms: D016977:Actinobacillus pleuropneumoniae / Q000502:physiology; D000822:Animal Husbandry; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D001424:Bacterial Infections / Q000097:blood / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D045705:Mycoplasma hyopneumoniae / Q000502:physiology; D016979:Pasteurella multocida / Q000502:physiology; D010998:Pleurisy / Q000097:blood / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D000069078:Seroconversion; D017011:Streptococcus suis / Q000502:physiology; D013552:Swine; D013553:Swine Diseases / Q000097:blood / Q000175:diagnosis* / Q000382:microbiology* / Q000473:pathology; D013997:Time Factors
chemical_list: D000907:Antibodies, Bacterial
keywords: Antibodies; Disease pattern; Pig; Pleuritis; Respiratory disease