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BVetMed - Additional content (Year 4) > LA Diagnostics and Vaccines > Flashcards

LA Diagnostics and Vaccines Flashcards

1
Q

What are the sample options on farm and when are these relevant?

A
  • bulk milk sample or split bulk tank test : any contagious disease
  • young stock check : BVD, if Ab+ then a carrier (if PI then will not have AB)
  • individual cows: TB or any eradication programme
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2
Q

Diagnostic options for identifying pathogen presence/exposure/disease?

A
  • antibody ELISA (with DIVA vax)
  • cell mediated response (g-INF test, skin test for TB)
  • pathogen ELISA or PCR (IBR)
  • pathogen culture
  • slaughterhouse
  • PM
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3
Q

What can you infer about a disease if older cows are AB+ but younger cows are AB-?

A
  • previous exposure to pathogen
  • active spreading nt likely or all cows would be affected
  • or different timing of a vax schedule
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4
Q

What pots should be used for serology samples?

A
  • serum pots (clots)

- RED or PLAIN

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5
Q

What pots should be used for PCR and Ag ELISA samples?

A
  • heparinised

- GREEN or PURPLE

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6
Q

What pots should be used for serology and PCR on milk?

A

Tube iwth preservative : DONT DIP IN BULK TANK! Contamination poss.

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7
Q

What pots should be used for culture of milk?

A

Sterile pot without preservative

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8
Q

What should be checked with the lab when interpretting test results?

A
  • sensitivty
  • specificity
  • NPV
  • PPV (predicting values)
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9
Q

IS the johnes test sensitive?

A
  • not very

- milk more sensitive than blood ?

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10
Q

What are the 2 types of prevalence of a disease that can be reported?

A
  • individual prevalence

- herd prevalence

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11
Q

What 2 types of testing can be used to identify disease in a herd? Which is more sensitive/specific?

A
  • Parallel (v spec, ^ sense)

- Series (^ spec, v sense) = confirmation testing. eg. skin test followed by g-IFN test for TB

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12
Q

What is the sense/spec of IBR testing?

A

Good

- generally good for viral, less good for bacterial

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13
Q

What 3 reasons may we be testing a herd?

A
  • testing for presence/prevalence (random samples)
  • testing ot eradicate (must test all individuals)
  • testing for abscnece ( eg. FMD so contagious that only few samples needed to prove not likely present)
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14
Q

How sense/spec is the TB test?

A
  • 99.9% spec
  • 80% sense
    > parallel testing so spec v and sesne^ ??
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15
Q

Give an eg of a disease you would want to eradicate? monitor? Tx? Vaccinate against the disease?

A
  • eradicate FMD
  • monitor BVDV
  • tx Leptospriosis to v excretion (zoonotic)
  • vax for
    > pathogen or toxin (eg. clostridium)
    > DIVA for dz
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16
Q

What must be remembered when thinking about treating a dz?

A

no point treating unless you can manage it at point of entry

  • GI worms, liver luke, claf scours, bTB, lepto, IBR
  • No vaccine for bad management!
17
Q

Outline concepts of disease management and which diseases are relevant to each

A
  • housing, hygiene, ventilation
  • colostrum management
  • all in all out concept (poultry)
  • stocking density (resp disease, environmental mastitis)
  • rotational grazing (GI worms)
  • Water trough management (IBR)
18
Q

How can poor disease management be identified from hx or records?

A
  • dry cow tube use
  • mastitis cow tube use
  • preventative tx with Halocur (Crypto scouring calf tx)
  • use of vax
    > always look at disease, farm management etc. before jumping to a quick fix
19
Q

Which diseases can cross react tests and vaccines?

A
  • TB test and Johnes vax
20
Q

How can vax be sued as part of disease management?

A
  • v pathogen load (lepto)
  • protect herd from reintroduction (BVD/IBR)
  • improve efficacy of current practice (rota/corona) eg . colostrum
    > typically raise herd immunity -> v pathogen load -> v infected animals -> infection dies out -> eradication
21
Q

Which type of infections are vaccines more effective for?

A
  • viral good

- bacterial less good

22
Q

How can vax interfere with testing? How can this be overcome?

A
  • most common testing based on serology
  • vaccines -> immune response
  • consider MDA
    > create sentinel groups that are not vaccinatede
  • if these test + for disese then it is naturally occouring in the herd
  • if consistently testing -ve may be able to stop vaccinating at some point
23
Q

What are DIVA vax?

A
  • differentiating infected from vaccinated animals
  • sensivity/specificity of the differentiating test
    > available for IBR, AI, FMD, bTB in development
24
Q

How do differing types of vaccine impact the response?

A
  • live: immunity v spread after inoculation
  • attenuated live: local immunity developee
  • deadL immunity response depends on adjuvant used
  • subunit vax eg. FMD AG presenting alfalfa (genetically modified)
  • toxin based for clostridial disease
  • boosters
25
Q

How long shuld a vaccine be used after opening?

A

within 24hours

- always check farm fridge

BVetMed - Additional content (Year 4) (34 decks)

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