Johne’s disease

Question 1

Johnes disease may be linked in what way to human health?

Answer 1

Link to Crohne’s disease
- through milk and milk products, meat, water, environment

Question 2

Johnes disease in seen in which cattle?

Answer 2

Older cattle - 3 years +
Often after calving

Question 3

What are the clinical signs of Johnes disease

Answer 3

Profuse diarrhoea (often with bubbles)
Weight loss
Animal remains bright and eating
Individual cases

Question 4

What are the effects of Johnes on production?

Answer 4

• Less milk yield in a lifetime
• 5X more likely to be lame
• 2X more likely to develop mastitis/SCC problems
• 1.8X more likely to suffer digestive/ respiratory disease

Question 5

How is Johnes transmitted?

Answer 5

80% of cases - Newborn calf
10% - young heifer
5% - before birth
5% - old heifers and cows

Question 6

Describe the infection routes of Johnes for young calves

Answer 6

• In utero
• Dirty environment
• Dam faeces
• Dam colostrum
• Pooled colostrum
• Waste milk

Question 7

Describe the 4 stages of Johnes disease

Answer 7

Stage 1.Silent infection. calves, youngstock - majority of cases
Stage 2. Sub-clinical disease. Shedders
Stage 3. Early clinical disease. Shedders
Stage 4. Advanced clinical disease - very small % of cases

Question 8

Which stages of Johnes are shedders?

Answer 8

2, 3 and 4

Question 9

When do dairy cows most commonly show clinical signs of Johnes disease?

Answer 9

Young cases – indicates heavy load of infection
See cases at calving – stress and hormones
Most commonly at 5yo

Question 10

In terms of Johne’s infection, what groups do you have in a herd?

Answer 10

Non-infected – no risk
Infected but non-shedding – no risk yet
Infectious – shedding – risk
- low shedders
- high shedders
- super shedders

Question 11

Describe faecal culture as a diagnostic tool for Johnes?

Answer 11

• Detects shedders (above a threshold ?)
• Time & cost
• “gold standard” in live animal
• SENS 50%-60%

Question 12

Describe faecal PCR as a diagnostic tool for Johnes?

Answer 12

New “gold standard” in live animal
Expensive (£30+)
Quicker than culture

Question 13

Describe ELISA as a diagnostic tool for Johnes?

Answer 13

Detects antibody
- Animal “losing the fight”
- Likely to be shedding
Older animals more likely to be ELISA positive

Question 14

Describe target sampling (30 cow screen) as a diagnostic tool for Johnes?

Answer 14

• Milk or blood antibody
• To detect infection in the herd
• Select the cows most likely to be +ve - thin, mastitis, lame, poor yield, older

Question 15

As a part of the national Johnes management plan what is the veterinary declaration for year 1 of phase II?

Answer 15

‘I can confirm that this farm has undertaken an assessment of Johne’s risk and status, and in my opinion has an appropriate and robust Johne’s management plan in place, which is compliant with the objectives of the National Johne’s Management Plan.’

Question 16

As a part of the national Johnes management plan what is the veterinary declaration for year 2 and 3 of phase II?

Answer 16

‘I can confirm that this farm has undertaken an assessment of Johne’s risk and status, and in my opinion has adopted the necessary management protocols to adhere to the appropriate and robust Johne’s management plan in place, which is compliant with the objectives of the National Johne’s Management Plan.’

Question 17

List the 6 control strategies involved in the national Johnes management plan

Answer 17

1. Biosecurity Protect and Monitor
2. Improved Farm Management
3. Improved Farm Management and Strategic Testing
4. Improved Farm Management Test and Cull
5. Breed to Terminal Sire
6. Firebreak Vaccination

Question 18

Name the 3 types of antibody testing strategy

Answer 18

Quarterly milk testing
Single test (pre dry off)
Double test (Pre Dry off and Pre Breeding)

Question 19

In which herds would you used quarterly milk testing?

Answer 19

• For herds of moderate-high prevalence not able to dedicate the resources or have the facilities required for IFM on all cows calving
• Frequent testing allows the creation of a low risk group (green cows, typically 90% of the herd) which are managed normally and a high risk group (red and amber cows) of cows which are separated at drying off into a dedicated segregation area to prevent contamination of green cows and green cow areas.

Question 20

Describe the Single test (pre dry off)

Answer 20

Used to segregate test positive cows at drying off into a dedicated area away from the low risk cows.
Not as sensitive as repeated testing and as such not all infectious animals may be identified allowing some to enter the calving area and spread the disease.

Question 21

Describe the double test (Pre Dry off and Pre Breeding)

Answer 21

Greater sensitivity than the single test and also provides a test result pre breeding to allow breeding decisions to be made.

Question 22

What is the Definition and Johnes infection status of green cows?

Answer 22

Low risk - no evidence of infection
ELISA negative for one or two tests

Question 23

What is the Definition and Johnes infection status of yellow cows?

Answer 23

Moderate risk - evidence of infection and may be shedding, should be managed as a risk factor
ELISA negative - but previously positive OR first positive ELISA test

Question 24

What is the Definition and Johnes infection status of red cows?

Answer 24

High risk - evidence of infection and highly likely to be shedding
Repeat ELISA positive - minimum of 2 tests

Question 25

How long should the test be between MAP ELISA and Tb testing?

Answer 25

60 days

Question 26

How can you reduce Johnes transmission to young stock?

Answer 26

1. Reducing the risk factors.
2. Cull animals likely to be shedding the infection.

Question 27

List the reducible risk factors of Johnes

Answer 27

• Avoid faeces.
• Calving area – snatch calving at birth.
• Clean calving pens.
• Calf pens / hutches – individual (?) clean.
• Keep young stock separate from adults.
• Colostrum – only feed dam’s colostrum.
• No pooled colostrum feeding.
• No waste milk feeding – throw it

Question 28

How can purchasing animals influence the Johnes risk

Answer 28

Only purchase from low risk herds
- No history of disease.
- Test negative on at least three occasions
- Faecal culture or PCR individual purchased animal

Question 29

Describe the Johnes vaccination

Answer 29

• “Gudair” authorised for sheep in U.K.
• Need authorisation from APHA to use
• Administered in 2nd week of life.
• Does NOT prevent infection.
• Reduces incidence of clinical disease.
• Interference with MAP antibody and TB testing.

Question 30

How can you improve farm management of Johnes in a beef suckler herd?

Answer 30

• Outdoor calving, Or move outside immediately calved
• Cull daughters
• Clip and clean teats before calving
• Ensure clean when purchasing bull