Johne’s Disease Flashcards
Why is MAP hard to control
Resistant to disinfectants and antibiotics
Survives >1yr on pasture; survives well in slurry and water
Can infect (and affect) other species
Sheep
Deer
Rabbits
What is Johne’s disease most common transmission route
Faeco-oral
When do majority (80%) of infection occur
First month of life
Cows infected Usually remain bright and appetent until terminal stages (T/F)
True
C/S for Johne’s in Dairy
Reduced milk yield
Reduced fertility
Poor body condition
Usually culled for poor performance
C/S for Johne’s in Beef
Poor fertility
Small calf born,calf does not do well
Poor condition
Diarrhoea
Peripheral oedema (Bottle jar)
Why is testing for Johnes tricky in regards to blood antibody levels
Takes 2-3 years to meet detection threshold
Antibody level ebbs and flows
Is antibodies effective
No. Only useful in testing
What samples detect MAP organism
Faecal PCR
Faecal Culture/Smear
What samples detect antibodies
Serum and milk ELISA
If cow is infected with MAP, what will a positive faecal smear Ziehl Nielhson
Clumps of acid fat
Faecal culture or faecal smear is gold standard
Faecal culture but takes a long time to grow
Johne’s disease treatment
NO TREATMENT BLEH. Get rid of animal.
What to do in a farm visit when controlling Johnes
Identify risk areas
Identify risk assessment
Discuss control
Step 1 in detecting MAP in dairy herd
Bulk tank antibody ELISA
Step 1 (beef) and step 2 (dairy) in detecting MAP
Sample proportion of herd to determine prevalence
Step 3
Individual screening
What is the age of cow to be blood tested for MAP
> 2 years
Johne’s accredited free must pass how many annual screening
3
Outline CHeCS disease status accreditation
Level 1-5. Completely voluntary
1- pass 3 annual test
2- not cleared 1
3- there is reactors but <3%
4- more than 3%
5- no testing
Why is beef cows harder to control transmission
less ability to manage transmission between infected dam/adults and young calves than dairy
Possibly increased chance of calves being exposed to other host (sheep/deer) as more likely to be outside during critical period (first month)
Environmental management probably most feasible (fencing off standing water etc.)
5 key concepts in controlling Johnes in beef/dairy
- Identify status of breeding cattle
- Seperate into neg and pos cow groups
- Biosecurity: establish status of new comers
4 .Keep replacements from negative-test cows and from calves that have had less infection-pressure (i.e. calved at grass) - Slurry and / or manure management: not on pasture grazed by youngstock; esp slurry from known positives
Johne’s control in dairy herds
As for beef, plus:
Don’t pool colostrum in herds with known Johne’s disease from cows with unknown / positive test status
“Herdwise” testing scheme
What is herdwise testing scheme
quarterly individual milk antibody testing used as a tool to control the disease within a herd.
traffic light system is used to categorise cows, and inform management decisions about which milk to collect for replacement feeding and animals testing positive are put into separate calving facilities.
all cattle are re-tested every 3 months when in milk, so decisions are less based on a single antibody result.
Repeat positives are culled as they are likely to have reduced milk yield and will be contributing to environmental contamination.
Is Johne’s vaccination effective
Not regular in UK. Not used much
