Johne's disease Flashcards
1
Q
What is seen with johnes disease?
A
- Older animals >3yr old
- Often after calving (stress)
- Profuse diarrhoea (often w bubbles)
- Weight loss
- Animal remains bright and eating
2
Q
Whats the most important transmission route for johnes?
A
- New born calves (0-4wks)
3
Q
What are the infection routes in young calves?
A
- In utero.
- Dirty environment.
- Dam faeces =
– Teats (wipe before calf suckles?)
– Contamination of environment - Dam colostrum.
- Pooled colostrum.
- Waste milk.
- Calf to calf
4
Q
What are ‘super-shedders’?
A
- > 1million cfu/g faeces
- 50kg faeces per day
- 50 billion cfu per day
- Theoretically can infect 50,000 calves a day
5
Q
How can johnes be diagnosed?
A
- Faecal culture +/or PCR - time + cost
- ELISA - detects antibody (high probability of being a shedder)
- Actiphage
- Gamma interferon - detect cell mediated immunity
6
Q
What cows would you select to test for johnes?
A
- The cows most likely to be +ve =
- thin
- mastitis
- lame
- poor yield
- older
7
Q
What are the different Johnes classification?
A
- J0 = repeat ELISA -ve - minimum 2 tests
- J1 = ELISA -ve - one test only
- J2 = ELISA -ve but positive within previous 3 tests
- J3 = ELISA -ve but positive on previous test
- J4 = ELISA +ve - 1st positive test
- J5 = Repeat ELISA +ve
8
Q
What is the risk of cross-reaction of TB + Johnes
A
- With TB test (mammalian) = false +ve in TB test
- With TB test (avian) = false -ve in TB test
- Should not Johnes ELISA test soon after TB test
9
Q
How can you control johnes disease?
A
- Reduce transmission to youngstock by =
- reducing risk factors
- cull animals likely to be shedding the infection
- possible faecal PCR testing of youngstock
10
Q
How can you reduce risk factors of johnes?
A
- 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
11
Q
What are other risk factors?
A
- Slurry & manure being spread on grazing.
(where else are you going to put it?) - Water courses – esp. stagnant ponds.
- Contamination of feeds.
- Other hosts =
– Sheep ?
– Wildlife – rabbits, deer