Monitoring & managing bovine infectious disease Flashcards
List the most common infectious diseases in cattle and sheep?
What is the 5 step Approach to infectious Disease ?
- Establish herd status -> active surveillance ; naive vs active infection
- Establish risk of exposure - movements, bioS
- Establish risk of spread -> vaccination & herd status
- Control the risks of exposure and spread
- Monitoring
What is the Se & Sp in diagnostic testing?
Se = the proportion of animals testing +ve among infected animals
* Sp = the proportion of animals testing -ve among non-infected
animals
What do we have to consider with diagnostic testing?
- likely population prevalence - exposure? pos & neg predictive values
- Testing strategies
Describe bulk milk sampling?
- Only lactatting cattle
- dilution effect
- influence of vaccination makes interpretation difficult
Describe cohort sampling?
** Sentinel cohorts -> naive, at risk animals
- opportunity for exposure
- Time for seroconversion - Youngstock post - MDA
**Statistical sampling
What family is BVD virus?
Flaviridae/ Genus: Pestivirus URT noise on auscultation
- 10
What are the different types of BVD?
-> Two genotypes
- BVDV type & - classical form
-BVDV type 2 - Severe acute BVD
-> Two biotypes
- non cytopathic
- cytopathic
Describe Transmission of BVD?
- Faecal-oral
- Discharges
- Transplacental
What are the two broad syndromes of BVD?
- Acute infection followed by immunity
- Persistent infection +/- Mucosal disease
Describe BVD clincial syndrome in Naive Adult Acttle
Describe clincial syndrome of BVD in Naive Calves ?
-> Pyrexia +/- Diarrhoea
-> immunosuppression ( resp dx; D+; other infectious)
-> Acute haemorrhagic enteritis + death (rare)
describe PI calves
- poor growth rates
- Immunosuppression
- Mucosal dx
BVD infection diagram
Describe Mucosal disease infecTIon?
- 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
What other things may we see with mucosal dx?
»+/- 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
Diagnosis of BVD ?
- 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
How can we confirm a PI in the live animal?
….
How do we establish herd status?
» Bulk milk tank
* Antibody ELISA
* Antigen PCR
» Individual testing
* Antibody ELISA (blood or milk)
* Antigen ELISA (blood, milk or tissue)
=> high Se & Sp
How to establish whether there was a recent, active BVDV infection?
……
How do we go about BVD eradication?
What monitoring and accreditation for BVD in dairy ?
» 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
What BVD monitoring & accreditation (beef)?
» 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
What are the 2 BVD vaccinations ?
- Bovilis
- Bovela