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mod 21 > IBR > Flashcards

IBR Flashcards

1
Q

what is IBR?

A

the most common clinical manifestation of dx that occurs during 1ary infection w BoHV-1

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2
Q

what does IBR stand for?

A

infectious bovine rhinotracheitis

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3
Q

what are the 3 subtypes of BoHV1?

A 
BoHV-1.1 = mainly causes IBR & can cause abortion
BoHV-1.2a = mainly cause IPV/IPB & can cause abortion 
BoHV-1.2b = mainly cause IPV/IPB but does NOT cause abortion
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4
Q

what does IPV & IPB stand for?

A

infectious pustular vulvovaginitis

infectious pustular balanophosthitis

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5
Q

what are the main glycoproteins which ab are produced against for BoHV-1?

A

glycoprotein E & B

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6
Q

every animal that has 1ary infection will go on to become latent: T/F?

A

true

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7
Q

stress can cause reactivation of BoHV-1, resulting in secondary infection: T/F

A

true

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8
Q

does virus shedding occur again at secondary infection?

A

yes

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9
Q

are there any CS for 2dary infection?

A

usually no CS

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10
Q

define naive animal

A

never been exposed to virus

no Ab present in blood unless MDA

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11
Q

what is the source of virus for 1ary infections?

A

other BoHV-1 infected animals

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12
Q

how is virus spread for 1ary infections?

A

mainly by direct contact:

  • resp secretions = nose to nose contact & aerosol w/i 3-5m
  • repro secretions (semen & female repro fluid)
  • indirect spread (fluid on outer clothing) has been documented
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13
Q

what CS are there for 1ary infections?

A 
dullness & reduced appetite
pyrexia
sudden reduced milk pdtn
conjunctivitis
nasal & ocular discharge
pharyngitis/tracheitis (URT signs)
rapid & loud breathing sometimes w cough
abortion (if virus crosses placenta)
embryo death (documented in maiden heifers)
neuro menigitis in neonatal calves
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14
Q

what are the viruses that can be involved in bovine resp dx complex?

A 
PI3
RSV
BoHV-1
BVDV
mycoplasma
pasteurella
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15
Q

what kind of ab response will there be for 1ary infections?

A

fast & sustained

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16
Q

where does the virus become latent in?

A

nerve ganglion

-usually dorsal root ganglion of trigeminal nerve w resp infection

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17
Q

does the ab titre persist in latent infections?

A

yes

18
Q

what can stimulate reactivation of latent infection?

A

stress:

  • calving
  • transport
  • high dose dexamethasone tx
  • lameness
  • dx
  • nutritional stress
19
Q

what CS are there in latent infection?

A

absent/v mild

20
Q

when will ab titre not be persistent in latent infection?

A

if infected during period of MDA cover - can lead to latent infection w/o circulating ab
sero-ve latent carrier

21
Q

diagnosis for BoHV-1?

A 
ocular conjunctival swab or guarded nasopharyngeal swab - direct test (ACUTE!) 
send to lab for:
PCR
virus isolation
FAT (fluorescent ab test)
serological ab testing
22
Q

what does serological ab testing test for?

A

ab to gE/gB
not useful for diagnosis of acute illness
ESSENTIAL for diagnosis & control @ herd lvl

23
Q

tx for BoHV-1? (acute)

A

NSAIDs
abs if animal @ risk of 2ary infection
consider vax in the face of infection if confirmed diagnosis

24
Q

what are vax licensed to do?

A

reduce severity of CS during 1ary infection
reduce shedding during 1ary infection
reduce likelihood & duration of shedding from reactivation

25
Q

do vaccines prevent latent infection/re-activation?

A

NO

26
Q

what vax are available?

A

live - marker/conven.
dead - marker/conven.
marker: gE +/- tK missing from surface

27
Q

which ELISA test will you choose to run at lab? (ab against gB or gE)

A

gE ELISA - ab against gE
if uninfected but marker vax: will be gE -ve
so if infected, will be gE +ve

28
Q

why might there be no CS during initial outbreaks of IBR?

A
  1. virus vary in virulence: diff virulent strains (7), genomic diff in strains
  2. resilience of animals: on better plan of nutrition, colostrum, no concurrent dx
  3. environment: good housing
29
Q

what is herd prevalence defined as?

A

number of infected herds/number of herds in country

30
Q

what is the approx herd prevalence of BoHV-1 for dairy & beef?

A

70% (dairy)

30% (beef)

31
Q

define animal prevalence of BoHV-1 (w/i affected herd)

A

number of infected cows/number of cows in herd
hugely variable: <5-100%
these indiv. animals are latent carriers

32
Q

goals of herd control?

A 
remain free from BoHV-1
eliminate BoHV-1 from herd ASAP 
prevent spread of BoHV-1  to dx free stock entering the herd in order to reduce w/i herd prevalence over time
or 
live w dx & min. impact
33
Q

ways to do herd diagnosis?

A

q1 - is herd infected? (any latent carriers?)
historical lab results: cheapest avai. method, spe excellent, se likely v poor
bulk milk ab test:
next cheapest for dairy herds: poor se when <20% of herd infected
test a proportion of indiv animals by ab test
-most exp & reliable
-“snapshot” = 30 animals > 9mth undergo Ab test (RANDOM selection)
0/1 +ve - 0-15% prevalence in herd
>1 +ve - >15% prevalence

34
Q

how to test which animals are LIKELY to be latently infected?

A

test a proportion of indiv. animals by ab test

-gets more reliable w increased no. of animals tested

35
Q

how to test which animals are latently infected?

A

must test ALL animals in herd

-most exp option, probably only appropriate in final stages of herd eradication program

36
Q

what is the aim of a herd that’s not infected?

A

remain free from BoHV-1

37
Q

aim of infected, low prev of latently infected animals for herd status?

A

eliminate BoHV-1 from herd ASAP

38
Q

aim of herd w infected, mod. or high prev of infected animals?

A

prevent spread of BoHV-1 into incoming stock in order to reduce prevalence over time

39
Q

what are the 3 elements of IBR control?

A

bio-exclusion
cull/isolate latently infected animals
regular, complete herd vax to reduce source & spread

40
Q

how to cull/isolate animals?

A

air-space isolation can prevent spread
increasingly impractical when more animals are latently infected (mod/high prev)
will not be appropriate for most herds

41
Q

when should culling/isolating animals be done?

A

low prev herds aiming for dx freedom

42
Q

can semen for AI be gE or gB ab +ve? (EU)

A

NO!! BoHV-1 shed in semen!
must NOT be infected OR vax against IBR
live vax can spread on farm!

mod 21 (12 decks)

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