title: Mycoplasma hyopneumoniae infection in pigs: duration of the disease and evaluation of four diagnostic assays.
abstract: 200 SPF pigs were infected by aerosol with Mycoplasma hyopneumoniae and the development of clinical signs, serological and pathological reactions were studied. Mean time to onset of coughing was 13 days. A mean delay of 9 days was observed from onset of coughing until seroconversion against M. hyopneumoniae as measured by ELISA. At an individual level, the sensitivity for this ELISA was estimated to 98-100% and the specificity to 93-100%. Pasteurella multocida was isolated from the majority of the lungs 4 weeks post inoculation with M. hyopneumoniae and the lung lesions in pigs were significantly larger when P. multocida was present as compared to pigs with M. hyopneumoniae alone. An evaluation of cultivation, immunofluorescence, ELISA and polymerase chain reaction for demonstration of M. hyopneumoniae in lungs showed that all four methods have a high sensitivity in the acute stages of pneumonia. In the later stages the sensitivity of cultivation was superior to the other methods. No differences in specificity were observed between the methods. The antigen-ELISA OD values and the immunofluorescence scores revealed a strong positive correlation. Nasal swabs were additionally used for demonstration of M. hyopneumoniae and the polymerase chain reaction was found superior to the other methods.
authors.affiliation: Federation of Danish Pig Producers and Slaughterhouses, Roskilde, Denmark. vis@sus.dk
authors.forename: V
authors.initials: V
authors.lastname: Sørensen
authors.forename: P
authors.initials: P
authors.lastname: Ahrens
authors.forename: K
authors.initials: K
authors.lastname: Barfod
authors.forename: A A
authors.initials: AA
authors.lastname: Feenstra
authors.forename: N C
authors.initials: NC
authors.lastname: Feld
authors.forename: N F
authors.initials: NF
authors.lastname: Friis
authors.forename: V
authors.initials: V
authors.lastname: Bille-Hansen
authors.forename: N E
authors.initials: NE
authors.lastname: Jensen
authors.forename: M W
authors.initials: MW
authors.lastname: Pedersen
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D016009:Chi-Square Distribution; D004797:Enzyme-Linked Immunosorbent Assay; D008168:Lung / Q000382:microbiology* / Q000473:pathology; D009174:Mycoplasma / Q000254:growth & development / Q000302:isolation & purification*; D009175:Mycoplasma Infections / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary*; D009297:Nasal Mucosa / Q000382:microbiology; D016979:Pasteurella multocida / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D012044:Regression Analysis; D013048:Specimen Handling; D013552:Swine; D013553:Swine Diseases
chemical_list: D000907:Antibodies, Bacterial