Why is Johne’s Disease important?
- Johne's disease causes adult cattle to waste and die. Clinical signs of diarrhoea and weight loss usually occur in cattle over 2 years of age. In heavily infected herds this leads to a high rate of wastage in cattle at 3 to 5 years old.
- Johne's disease affects other ruminant species
- Johne’s disease has been found in rabbits
- The bacterium that causes Johne's disease (Mycobacterium avium subspecies paratuberculosis, abbreviated to MAP) has been linked to the human disease of the bowel, Crohn’s disease. While no direct link between the two diseases has yet been shown to exist, both the Food Standards Agency and DEFRA advise the dairy industry to take precautionary measures to minimise the number of Johne’s disease organisms entering milk.
How is Johne’s Disease transmitted?
- MAP is shed in large numbers in faeces and can be found in colostrum and milk.
- Animals are infected by ingesting MAP.
- Young animals are most susceptible to infection.
- MAP infection is usually introduced to a herd by purchasing infected breeding stock including bulls.
- Semen can be infected in the later stages of the disease and this is a low risk for disease transmission.
Note that this page is a guide to the disease and the testing programmes. It does not cover all testing outcomes or variations in testing programmes for the control and eradication of Johne’s disease.
How is Johne’s Disease Controlled?
For herds that sell breeding stock there is a risk level accreditation programme that allows purchasers to assess the risk posed by herds selling breeding stock. Herds that are controlling the disease may use the risk level accreditation programme too or restrict themselves to the disease reduction programme.
To determine the best approach for your herd we recommend that you discuss your objectives for the herd with your veterinary surgeon. At this meeting the herd biosecurity can be reviewed and upgraded to meet with the scheme requirements and a health plan formulated to specifically address the requirements of Johne’s disease control.
A testing programme is only one aspect of control, and improving hygiene within the herd to reduce the amount of faeces from adults that young calves are exposed to is essential. Practices such as feeding pooled colostrum or waste milk are high risk and must be avoided. As MAP can survive in the environment for prolonged periods and rabbits can be infected a whole farm approach to control is required.
Tests on the live animal tend to detect infection in the later stages of the disease and infected animals may test negative for several years before testing positive. All this means that control and eradication is difficult and is usually a lengthy procedure.
Vaccination may be useful in heavily infected herds. Vaccination will not remove the infection from the herd and is not recommended for use in herds that are selling breeding stock.
- Johne’s disease is an important cause of financial loss to British beef and dairy farmers.
- The bacterium that causes Johne’s disease may be a danger to human health
- SAC provides an effective Johne’s Disease Screening and Eradication Programme for infected herds
- The Johne’s Disease Risk Level Accreditation programme provides assurance that an effective test and control programme is in place.
- The Scheme is licensed by CHeCS and all tests are accredited by UKAS to ISO17025.
Johne’s Disease Risk Level Accreditation Programme
- Review and upgrade herd biosecurity programme to meet the rules of the scheme (see rules summary or CHeCS technical document).
- Put in place a health plan to address the requirements of the Johne’s disease risk level programme
- Test all animals of two years of age and older.
- Where all animals test negative this is a clear herd test.
Level 1: there have been three clear annual herd tests. This is the lowest level of risk.
Level 2: There has a current clear herd test, but has not yet gained level 1 status.
Level 3: At the most recent herd test there are reactors in the herd at the level of three percent or fewer.
Level 4: There has been more than three percent reactors at its most recent herd test.
Level 5: Those herds without a health plan for Johne’s disease and that do not adhere to the mandatory elements of the health plan are Risk Level 5. This is the highest level of risk and additionally applies to herds that carry out no testing.
Once a herd has been accredited at Level 1 achieved two further clear tests, with more than 20 home-bred adults in the herd, the herd can opt for biennial testing providing all cull cows and animals not born in the herd are tested in the intervening year.
Johne’s Disease Reduction Programme
- This programme does not carry any accreditation and can be used as a flexible approach to the control of Johne’s disease in commercial herds that do not sell breeding stock.
These control programmes are applicable to both beef and dairy herds. Milk samples may replace blood samples in the dairy herd.
CAN YOU AFFORD TO TAKE THE RISK?