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Research comment
Johne’s disease control: a challenging yet achievable goal
  1. Sam Strain, BVMS, PhD, MRCVS
  1. Animal Health & Welfare Northern Ireland, Dungannon, BT71 6JT, UK
  1. E-mail: sam.strain{at}

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Johne’s disease is an infectious disease of ruminants caused by the bacterium Mycobacterium avium subspecies paratuberculosis (Map). It is found globally and is undoubtedly one of the most challenging infectious diseases to control in farmed livestock.1 The challenges stem from its long incubation period, as well as the difficulty in accurately identifying the infection. All tests for Johne’s disease have poor sensitivity particularly in the preclinical phase of infection with antibody detection tests having a suboptimal specificity.2 However, the study by Gavin and others,3 summarised on p 483 of this week’s issue of Vet Record, indicates that control and apparent eradication of the infection is achievable, at least at the individual herd level.

While there are numerous potential routes by which infection can enter a herd, overwhelmingly, the most important is through the introduction of infected animals.4 The report by Gavin and others illustrates this well. In this case, the most likely route that infection was introduced in to the goat herd was through the importation of infected animals, despite all imported animals having tested negative for Johne’s disease by either agar gel immunodiffusion (AGID) or ELISA. This highlights the substantial risk of relying on point-of-sale testing for Johne’s disease to give purchasers any assurance of the true Johne’s disease infection status of individual animals.

The safest way to prevent infection introduction …

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