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
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2
Q

Whats the most important transmission route for johnes?

A
  • New born calves (0-4wks)
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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
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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
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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
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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
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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
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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
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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
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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
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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
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