title: Effectiveness of Gudair™ vaccine for the control of ovine Johne's disease in flocks vaccinating for at least 5 years.
abstract: OBJECTIVE
  Examine the prevalence of shedding of Mycobacterium avium subsp. paratuberculosis (Mptb) at least 5 years after starting vaccination with Gudair™ in flocks of varying initial prevalence of ovine Johne's disease (OJD) and identify risk factors for variation in vaccine efficacy.
  
  
  METHODS
  Pooled faecal culture (PFC) was conducted for 41 flocks from southern NSW and Victoria to determine estimates of current OJD prevalence. The data were compared to estimates of prevalence at or prior to commencement of vaccination at least 5 years earlier, based on available serological or PFC tests when vaccination commenced. A cross-sectional study was conducted to identify risk factors for differing prevalence levels in 36 of the flocks.
  
  
  RESULTS
  Historical data enabled classification of 37 flocks as high (13; 35.1%), medium (10; 27.0%) or low (14; 37.8%) estimated initial OJD prevalence. Results of PFC in 2008-09 identified that 81.1% (30/37) of flocks had detectable shedders, with 48.6% (18/37) flocks still classified as medium or high OJD prevalence, including 50% (7/14) of flocks initially classified as low prevalence. Shedding was not detected in 18.9% (7/37) flocks. Flocks with OJD prevalence exceeding 1% at 5 years or more following the commencement of vaccination were associated with reports of sheep straying and introduction of new sheep.
  
  
  CONCLUSIONS
  Despite significant declines in estimated OJD prevalence following vaccination for ≥5 years, 81.1% of flocks were shedding Mptb and considered at risk of spreading the disease or suffering recrudescence of losses if vaccination were to cease. Flock managers are advised to persist with vaccination.
authors: Faculty of Veterinary Science, University of Sydney, PMB 3, Camden, New South Wales, 2570, Australia. peter.windsor@sydney.edu.au.
authors: P A
authors: PA
authors: Windsor
authors: J
authors: J
authors: Eppleston
authors: N K
authors: NK
authors: Dhand
authors: R J
authors: RJ
authors: Whittington
mesh_terms: D000818:Animals; D003430:Cross-Sectional Studies; D005243:Feces / Q000382:microbiology; D016014:Linear Models; D016927:Mycobacterium avium subsp. paratuberculosis / Q000276:immunology*; D009517:New South Wales / Q000453:epidemiology; D010283:Paratuberculosis / Q000453:epidemiology* / Q000276:immunology* / Q000517:prevention & control; D015995:Prevalence; D012307:Risk Factors; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology* / Q000276:immunology* / Q000517:prevention & control; D011795:Surveys and Questionnaires; D032581:Tuberculosis Vaccines / Q000494:pharmacology*; D014739:Victoria / Q000453:epidemiology; D017201:Virus Shedding / Q000187:drug effects
chemical_list: D032581:Tuberculosis Vaccines
keywords: disease management; mycobacteria; ovine Johne's disease; paratuberculosis; sheep; vaccination