Johne's Disease

The Disease
Johne's disease is caused by the bacterium Mycobacterium avium subspecies paratuberculosis. Infection is targeted to the intestine wall, causing damage which results in a slow wasting disease characterised by loss of condition, scouring and death (or culling). Young animals are most susceptible, but the disease has a long incubation period and is not usually noticed until the animals pass 18 months of age.

Biobest also offer a (non CHeCS) Johne's Risk Assessment Programme, designed to provide vets and farmers with a first step towards understanding and managing Johne's in a herd.

The Effect in Your Herd
In heavily effected herds a high rate of wastage is seen in cattle at 2-4 years of age. Average annual losses are estimated at £2,600 in a 100 cow dairy herd, and £1,600 in a similar sized beef herd.

The Route of Transmission
The bacterium is shed in large quantities in the faeces of infected animals, and the calves of affected animals are nearly always positive and require to be culled. The slow development of the disease means that spread of infection occurs before an animal can be detected as positive, and makes it hard to eradicate. Vaccination may prevent some clinical disease, but does not prevent re-infection of the herd. Pasture becomes contaminated and ideally should be left for a year before cattle are allowed to graze.