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.

The Effect in Your Herd

In affected herds a high rate of wastage and increased culling rates are often seen in cattle between 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. (figures from NADIS bulletin 2007)

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.

Disease & Status	Animals to be tested	Action required
1. Herd test	All animals of 2 years or older are tested	If clear, repeat after 12 months. Three clear annual tests allow accreditation. If positive, move to step 2.
2. Disease reduction	All animals of 2 years or older tested annually, quarterly testing may be useful in dairy herds.	Positive animals removed and management practices addressed to limit new infections.
3. Maintenance of accreditation	The herd test as in step 1 is repeated annually Or Biennial testing may be an option in herds that have been accredited for at least 3 year	If clear, accreditation is maintained. Consult HiHealth Herdcare if you wish to discuss the biennial testing option.

Disease & Status

Animals to be tested

Action required

1. Herd test

All animals of 2 years or older are tested

If clear, repeat after 12 months. Three clear annual tests allow accreditation.

If positive, move to step 2.

2. Disease reduction

All animals of 2 years or older tested annually, quarterly testing may be useful in dairy herds.

Positive animals removed and management practices addressed to limit new infections.

3. Maintenance of accreditation

The herd test as in step 1 is repeated annually

Biennial testing may be an option in herds that have been accredited for at least 3 year

If clear, accreditation is maintained.

Consult HiHealth Herdcare if you wish to discuss the biennial testing option.

*if too many animals require removal, there are other options, e.g. vaccination, which may be used, and this will be discussed in detail when the results are reported.