johnes Flashcards

1
Q

explain aetiology of johne’s dx

A
caused by MAP 
resistant to disinfectants & abs
survives >1y on pastures, survives well in slurry & water
can infect other species:
-sheep
-deer
-rabbits
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what does MAP stand for?

A

mycobacterium avium subspecies paratuberculosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

epidemiology of johne’s?

A

transmission:
faeco-oral
transplacental
via milk/colostrum

w/i & btwn farms
btwn host species? potentially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

when do 80% of johne’s infections occur?

A

within 1st month of life

=particularly susceptible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are animals infected w MAP called?

A

supershedders

-can shed up to 100mil organisms/kg faeces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

which animal group is most susceptible to MAP?

A

calves! (transplacental!)

less likely for older animals to pick up infection but still poss.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

economical impacts of johne’s?

A

diff to estimate bcs:
-subclinical
-infected animals often culled for other reasons: lameness, infertility, reduced milk
can be high if valuable bull
becomes apparent @ age 3-5 so may impact greater in beef breeding animals due to reduced productive lifespan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

where does MAP localise in the body?

A

GIT

-cell-mediated immune resp. may/may not eliminate MAP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does MAP cause after localising in GIT?

A

chronic, granulomatous enteritis

thickening of intestinal wall, esp terminal ileum > results in PLE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

CS of PLE?

A

decreased albumin (hypoabluminaemia)
prog. weight loss
D+
oedema

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

CS of johne’s (dairy)?

A

usually remain bright & appetent until terminal stages
reduced milk yield
increased ICSCC
reduced fertility
poor BCS
usually culled for poor perf: not v specific, can see increased culling rates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

CS of johne’s (beef)?

A
poor fertility
small calf born, does not do well 
poor BCS
D+
peripheral oedema 
beef under less pdtn P
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

diagnosis of johne’s dx?

A
hx (herd & indiv lvl)
CS
detect ab:
-serum ELISA
-milk ELISA
detect MAP organism:
-faecal PCR
-faecal smear
-faecal culture
-PM & histho
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

when do animals start producing Ab against MAP?

A
about 18mths of age
gradual increase (can take up to 3y to hit detection threshold!)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

if detect animal is infective but not showing CS = what stage?

A

preclin stage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how is serum ELISA testing carried out?

A

screening test
serology = plain tube ~50% se: false -ves poss.
99% spe
but beware after tb test! false +ves

17
Q

how is milk ELISA testing carried out?

A

screened quarterly via milk recording
less se
false -ves & +ves
provides basis for many dairy herd control programmes

18
Q

what to look out when doing faecal smear?

A

clumps of acid fasts
use Ziehl-Nielsen stain
false -ves v poss.

19
Q

what diagnostic test is gold standard?

A

faecal culture

but can take several months

20
Q

what is ELISA often used in conj w?

A

PCR testing - secondary test in some screening prog

more sensitive

21
Q

what tests are used to establish herd status?

A

bulk tank ELISA: useful starting point but insensitive esp in low prev herds = false -ves
blood serology: 30 cow screen - select based on age/ICSCC
-all animals >2y

22
Q

bioexlusion, test & cull strategies same as IBR (but no vax included! have vax but only avai. by import)

A

-

23
Q

what entails the test & cull screening test?

A
ELISA-based
-blood test all animals >2y annually 
-milk ELISA test quarterly
cull +ves @ convenient time
manage +ve cows as 'leper colony'
johne's accredited free = 3x annual clear test
24
Q

CHeCS dx status accred. lvl 1 =?

A

have been 3 clear annual herd tests

lowest lvl of risk

25
Q

CHeCS dx status accred lvl 2?

A

current clear herd test, but not yet gained lvl 1 status

26
Q

CHeCS dx status accred. lvl 3?

A

at most recent herd test there are reactors in herd @ lvl of 3% or lower

27
Q

CHeCS dx status accred. lvl 4?

A

> 3% reactors @ most recent herd test

28
Q

CHeCS dx status accred. lvl 5?

A

w/o health plan for johne’s & do not adhere to mandatory elements of heath plan
highest risks & applies to herds that carry out NO testing

29
Q

CHeCS dx status accred. lvl 5?

A

w/o health plan for johne’s & do not adhere to mandatory elements of heath plan
highest risks & applies to herds that carry out NO testing

30
Q

control for johne’s?

A
general management advice
calf rearing
cleanliness
colostrum
replacement milk
pasture/slurry
rmb to test bulls!
31
Q

difficulties in johne’s control in beef herds?

A

less ability to manage transmission btwn infected dam/adults & young calves than dairy
-beef suckler system: allows transmission c.f. dairy where can remove calf rapidly
possibly increased chance of calves being exposed to other host (sheep/deer) as more likely to be outside during critical period (1st month)
environmental management probs most feasible (fencing off standing water etc.)

32
Q

steps for control of johne’s?

A
  1. identify status of breeding cattle
  2. separate +ve and -ves cow groups
  3. establish status of incoming stock
  4. keep replacements separate from -ve cows & calves that had less infection P e.g. birthed @ grass
  5. slurry and/or manure management: not on pasture grazed by youngstock; esp slurry from known +ves
33
Q

johne’s control in dairy herds?

A

same as beef
+
don’t pool colostrum in herds w known status from cows w unknown/+ve test status
“herdwise” testing scheme

34
Q

what is herdwise?

A

quarterly indiv milk ab testing used to control dx w/i herd
traffic light system used to categorise cows & inform management decisions about which milk to collect for replacement feeding & animals testing +ve are put into separate facilities
all cattles retest q3mth when in milk, decisions less based on single ab result
repeat +ves are culled bcs likely to have reduced milk yield & contribute to environmental contamination (red cat)

35
Q

herdwise: green indicates?

A

milk/colostrum for replacements
-group calving
(low risk)

36
Q

herdwise: yellow indicates?

A

calving facilities
-indiv calving pens
(high risk!)

37
Q

herdwise: red indicates?

A

cull repeat +ves prior to next calving

  • environ. contamination
  • min. milk & slaughter losses