Johnes Disease

Johnes TASHA Animal Health Ireland Scheme

Interesting Facts

  • Johnes is caused by mycobacterium avium Paratuberculosis (MAP)
  • The bacteria lays dormant in the gut in the payers patches (lymph tissue) until later in life when it can cause clinical disease
  • It is spread only from adult animals to calves as the gut walls closes to susceptibility fully after one year (No adult to adult spread)

Clinical Signs

  • Weight Loss
  • Scour
  • Bottle JAw
  • Milk Drop

Clinical Johnes is thankfully rare due to testing but it can be summed up as a chronic wasting disease. Usually seen in cows between 4 + 8 years old but it has been seen in heifers .



  • Blood Antibody Elisa
  • Milk Antibody Elisa
  • Faecal PCR – Ancillary test to a positive blood or milk
  • Faecal culture – Historical ancillary test

Treatment – NONE



  • Focus on keeping calves away from positive cows faeces and colostrum collection and separate housing area.
  • Identifying the positive or inconclusive cows by regularly testing BUT cannot be within 3 months of a Tb test (due to interaction with the avian TB injection.
  • Colostrum management – avoiding pooled colostrum using negative own mothers colostrum to calf.
  • Pasteurisation could be a viable option for some farms
  • Slurry Management of calf pastures and feed preservation.

These are only some measures you can take to try and prevent the disease as it is a very complex disease . Contact your vet about signing up to the AHI programme if concerned .