title: Effect of Mycoplasma hyopneumoniae colonization at weaning on disease severity in growing pigs.
abstract: To determine whether Mycoplasma hyopneumoniae colonization at weaning in off-site weaning systems is associated with the severity of respiratory disease due to this agent in growing pigs, we studied 20 groups, each group representing a different week in production, in sow herds at 3 farms of 3000 sows each that had a prevalence of M. hyopneumoniae colonization at weaning higher than 5%. The calculated sample size for assessment at weaning was 39 piglets for each group under study; 39 litters were randomly selected, and 1 piglet was randomly selected from each litter for testing and ear-tagged. In total, 780 piglets were tested. The presence of M. hyopneumoniae in nasal swabs at weaning was established by nested polymerase chain reaction (PCR). All groups were followed until slaughter, at which time blood samples were collected from each ear-tagged pig to test for M. hyopneumoniae antibodies, bronchial swabs were collected for detection of M. hyopneumoniae DNA by nested PCR, and the lung lesion score and percentage of affected lungs in the same animals were calculated. Correlation analyses showed a positive correlation between colonization at weaning and all 4 dependent variables indicating infection at slaughter: average lung lesion score, percentage of affected lungs, presence of M. hyopneumoniae on the bronchial epithelium, and seroconversion. This study provides evidence that severity of the disease can be predicted by the prevalence at weaning in segregated systems. Therefore, strategies focused on reducing colonization at weaning seem to be important elements in the global control of M. hyopneumoniae in segregated production systems.
authors: Swine Disease Eradication Center, College of Veterinary Medicine, 385 Animal Science/Veterinary Medicine Building, University of Minnesota, 1988 Fitch Avenue, St. Paul, Minnesota 55108, USA. fano0001@umn.edu
authors: Eduardo
authors: E
authors: Fano
authors: Carlos
authors: C
authors: Pijoan
authors: Scott
authors: S
authors: Dee
authors: John
authors: J
authors: Deen
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D004269:DNA, Bacterial; D008168:Lung / Q000382:microbiology / Q000473:pathology; D045705:Mycoplasma hyopneumoniae / Q000276:immunology / Q000302:isolation & purification*; D045729:Pneumonia of Swine, Mycoplasmal / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D016036:Seroepidemiologic Studies; D012720:Severity of Illness Index; D013552:Swine / Q000254:growth & development*; D014886:Weaning
chemical_list: D000907:Antibodies, Bacterial; D004269:DNA, Bacterial
references: Vet Rec. 1965 Apr 3;77:383-7
references: 14330219
references: Can J Vet Res. 2005 Jul;69(3):223-8
references: 16187553
references: Vaccine. 2000 Jan 18;18(13):1244-52
references: 10649626
references: Vet Microbiol. 2000 Oct 1;76(3):299-303
references: 10973704
references: Can J Vet Res. 2002 Apr;66(2):79-85
references: 11989738
references: J Vet Med B Infect Dis Vet Public Health. 2002 Sep;49(7):349-53
references: 12420871
references: J Vet Diagn Invest. 1999 May;11(3):246-51
references: 10353356
references: Can J Vet Res. 2004 Jan;68(1):12-8
references: 14979430
references: Vet Rec. 2004 Jul 10;155(2):57-8
references: 15285285
references: J Am Vet Med Assoc. 1990 Oct 15;197(8):1025-9
references: 2243034
references: Vet Microbiol. 1990 Nov;25(2-3):177-92
references: 2126409
references: Vet Microbiol. 1997 Jan;54(1):23-34
references: 9050168
references: J Vet Diagn Invest. 2002 Nov;14(6):463-9
references: 12423027