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Changes in Within-Flock Prevalence of Mycobacterium Avium Paratuberculosis Shedding Following Vaccination

Project  OJD.033 was a longitudinal observational study examining the efficacy of GudairTM in  decreasing the prevalence of shedding of infectious organisms following the  commencement of vaccination in flocks varying in initial OJD prevalence.  Twelve flocks were examined over a 6 year period, 3 with high, 5 with medium  and 4 with low OJD prevalence at the commencement of the study. Changes in  the prevalence of shedding as the proportion of vaccinates in the flock  increased were estimated and it was found that vaccinates had significantly  lower prevalence of shedding than unvaccinated sheep (0.63% versus 1.66%;  P<0.001). However a significant observation was that at the final sampling  when all adult sheep had been vaccinated as lambs, a total of 10 of the 11  flocks still in the study had sheep with detectable shedding, ranging from  0.13% to 1.29%. The persistence of shedding for an extended period following  onset of vaccination presents a risk for spread and recrudescence of OJD. It  is recommended that the study be continued for a further 3 rounds of testing  to provide additional data on the rate of decline of shedding in flocks now  composed entirely of ‘second generation vaccinates’. This will assist sheep  producers to assess the risks of ceasing vaccination and purchasing  vaccinated re-stocker sheep.


Title Size Date published
166.0KB 22/10/2010


Contract No. Title Start date End date Funding type
Changes in Within-Flock Prevalence of Mycobacterium Avian Paratuberculosis Shedding Following Vaccination with Gudair in High & Low Prevalence Flocks
01/09/2002 03/06/2009

This page was last updated on 06/07/2018

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