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PRODUCTION VMS4008 > Monitoring & managing bovine infectious disease > Flashcards

Monitoring & managing bovine infectious disease Flashcards

1
Q

List the most common infectious diseases in cattle and sheep?

A
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2
Q

What is the 5 step Approach to infectious Disease ?

A
  1. Establish herd status -> active surveillance ; naive vs active infection
  2. Establish risk of exposure - movements, bioS
  3. Establish risk of spread -> vaccination & herd status
  4. Control the risks of exposure and spread
  5. Monitoring
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3
Q

What is the Se & Sp in diagnostic testing?

A

Se = the proportion of animals testing +ve among infected animals
* Sp = the proportion of animals testing -ve among non-infected
animals

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4
Q

What do we have to consider with diagnostic testing?

A
  • likely population prevalence - exposure? pos & neg predictive values
  • Testing strategies
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5
Q

Describe bulk milk sampling?

A
  • Only lactatting cattle
  • dilution effect
  • influence of vaccination makes interpretation difficult
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6
Q

Describe cohort sampling?

A

** Sentinel cohorts -> naive, at risk animals
- opportunity for exposure
- Time for seroconversion - Youngstock post - MDA

**Statistical sampling

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7
Q

What family is BVD virus?

A

Flaviridae/ Genus: Pestivirus URT noise on auscultation
- 10

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8
Q

What are the different types of BVD?

A

-> Two genotypes
- BVDV type & - classical form
-BVDV type 2 - Severe acute BVD

-> Two biotypes
- non cytopathic
- cytopathic

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9
Q

Describe Transmission of BVD?

A
  • Faecal-oral
  • Discharges
  • Transplacental
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10
Q

What are the two broad syndromes of BVD?

A
  • Acute infection followed by immunity
  • Persistent infection +/- Mucosal disease
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11
Q

Describe BVD clincial syndrome in Naive Adult Acttle

A
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12
Q

Describe clincial syndrome of BVD in Naive Calves ?

A

-> Pyrexia +/- Diarrhoea
-> immunosuppression ( resp dx; D+; other infectious)
-> Acute haemorrhagic enteritis + death (rare)

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13
Q

describe PI calves

A
  • poor growth rates
  • Immunosuppression
  • Mucosal dx
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14
Q

BVD infection diagram

A
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15
Q

Describe Mucosal disease infecTIon?

A
  • Oropharynx - ulcers, hyperaemia, oral apain, pytalism, reduced appetite/ anorexia
  • Muzle - ulcers, dried cracked inflamed rhinarium
  • Gut - ulcers, profuse, homogenous D+
  • Feet - ulcers in interdigital cleft
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16
Q

What other things may we see with mucosal dx?

A

»+/- dermatitis (scabs and skin crusts) - heels, perineal region and
between the hind legs
»Eyes – Lacrimation, epiphora +/- crusting
»Nose – Mucopurulent discharge +/- crusting
»Rapid loss of condition

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17
Q

Diagnosis of BVD ?

A
  • CLS
  • PME
  • Lesions throughout the alimentary tract
  • Transverse palatine ulcers
  • Longitudinal oesophageal ulcers
  • Depletion of gut-associated lymphoid tissue (GALT) ± underlying lymph nodes
  • Lab testing
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18
Q

How can we confirm a PI in the live animal?

A

….

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19
Q

How do we establish herd status?

A

» Bulk milk tank
* Antibody ELISA
* Antigen PCR

» Individual testing
* Antibody ELISA (blood or milk)
* Antigen ELISA (blood, milk or tissue)

=> high Se & Sp

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20
Q

How to establish whether there was a recent, active BVDV infection?

A

……

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21
Q

How do we go about BVD eradication?

22
Q

What monitoring and accreditation for BVD in dairy ?

A

» Annual youngstock screen
* 9-18 month old animals, unvaccinated
* Separately managed groups
» Quarterly bulk milk PCR
» First lactation heifer test (milk antibody)
» “Tag and testing” (calf virus test)
» Confirm and remove PI animals
» Establish status of purchased stock

23
Q

What BVD monitoring & accreditation (beef)?

A

» Annual youngstock screen
* 9-18 month old animals, unvaccinated
* Separately managed groups
»“Tag and testing”
»Screening breeding herd (excluding ones that
have negative calves)
»Confirm and remove PI animals
» Establish status of purchased stock

24
Q

What are the 2 BVD vaccinations ?

A
  • Bovilis
  • Bovela
25
Describe Bovilis Vaccine?
* Inactivated, cytopathic BVD 1 * 2 doses, 4 weeks apart * 6 monthly revaccination
26
How would we use Bovilis?
For active immunisation of cows and heifers from eight months of age onwards to protect the foetus against transplacental infection with Bovine Viral Diarrhoea virus.
27
how to vaccinate Bovela?
* Modified live, non-cytopathic BVD 1 and 2 * Single dose * Annual revaccination
28
When to use Bovela?
For active immunisation of cattle from 3 months of age to reduce hyperthermia and to minimise the reduction of leukocyte count caused by bovine viral diarrhoea virus (BVDV-1 and BVDV-2), and to reduce virus shedding and viraemia caused by BVDV-2. For active immunisation of cattle against BVDV-1 and BVDV-2, to prevent the birth of persistently infected calves caused by transplacental infection.
29
What is the use of BVD vaccine during pregnancy?
It is recommended to vaccinate before pregnancy to ensure protection against persistent infection of the foetus. Longlasting viremia has been observed after vaccination, in particular in pregnant seronegative heifers (10 days in a study). This may result in transplacental transmission of the vaccine virus, but no adverse effects on foetus or pregnancy was observed in studies. Shedding of the vaccine virus by body fluids cannot be excluded. T
30
What causes Johne's dx?
Mycobacterium avium subsp paratuberculosis
31
Transmission of Johne's?
* Ingestion or transplacental * Faeces > Colostrum > Milk > In utero * Risk of infection decreases with age
32
Johne's CLS?
* Diarrhoea * Weight loss / poor BCS * Reduced milk yield * Submandibular oedema (Bottle jaw) * Immunosuppression (e.g. high SCC)
33
What two main diagnostics for Johne's dx?
- Antibody ELISA - Faecal PCR
34
Describe Antibody ELISA for Johne's detection?
* Cell-mediated immune response * Low sensitivity (30-70%) → false negatives * Reasonable specificity * Repeated sampling * Blood / milk samples
35
Describe Faecal PCR for Johne's dx?
* Intermittent shedding * Low sensitivity, high specificity * Useful for index cases in low prevalence herds
36
T/F Limitations of diagnostic testing make 'true' eradication impossible
True
37
What might be risk of exposure to Johne's ?
» Unknown positives * Bought-in cattle * Break-ins from neighbouring farms » Inadequate biosecurity * Infected faeces * Slurry spreading * Water courses * Fomites (e.g. machinery)
38
What are some of the biggest risks of spread of Johne's?
- Unknown positives - Calving environment - Colostrum management - Youngstocck management
39
Johne's accreditation?
»1. Johne’s Disease Risk-Level Certification Programme (beef and dairy) »2. The Johne’s Disease Risk-Level Reduction Programme (dairy)
40
What is IBR?
Bovine herpes virus 1 subtypes 1.1 & 1.2
41
IBR - long term infectious status?
» Any animal with antibodies is a lifelong latently infected carrier, and is a risk to other cattle
42
Pathophysiology of IBR?
=> Neuro-invasion via trigeminal ganglion * Re-activation from latency in stressed animals * Re-activation of virus may or may not lead to re-excretion and clinical signs * Animals with high antibody titre are less likely to re-excrete virus
43
Risk factor to IBR?
Bought in animals! * Can survive in environment for 13 days * Aerosol transmission up to 4.4m
44
CLS of IBR?
» Clinical signs in 2-3 days, lasting ~10 days * Pyrexia, epiphora/rhinorrhoea (serous to mucopurulent- nasal ulceration), conjuntivitis, tachypnoea, cough, abortions) * Abortion might occur several months later (>5 months) * Secondary bacterial infection
45
Describe IBR in calves?
» Calves – can be fatal * Necrotic lesions in GI mucosa * MDA protection until ~6 months old from clinical disease, but can be infected and become latent
46
What is the venereal form of IBR?
infectious pustular vulvovaginitis and balanoposthitis
47
How do they get that?
» Not from viraemia from respiratory tract » From contaminated semen (either natural service or AI) » Genital mucosa becomes oedematous, hyperaemia, with small pustules that coalesce to form yellow-white fibrinous membranes that can form ulcers
48
What can happen as a consequenceS?
» Get latent infection in the sacral ganglia, with subsequent virus re-activation »Infected bulls excrete virus in semen - predominantly seminal fluid
49
How can we confirm diagnosis of IBR?
...
50
Vaccination for IBR?
- The marker vaccine has the non)essential glycoprotein E deleted -> * Vaccinated animals are gE -ve in contrast to field strain infected cattle » The vaccine is good at preventing clinical disease and reduced spreading, but doesn't prevent field virus from causing a limited infectionA
51
Accreditation for IBR?
»“There are three standard CHECS programmes for IBR: * Accredited Free (AF) Programme * Vaccinated Monitored Free (VMF) Programme * Eradication Programme * A gE marker vaccine may be used in all programmes and must be used in the IBR VMF programme.”

PRODUCTION VMS4008 (34 decks)

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