BVD

Question 1

What type of virus is BVD

Answer 1

pestivirus

Question 2

What are the 2 types of BVD and how prevalent is it

Answer 2

BVDv Type 1: prevalent
BVDv Type 2 rare

Question 3

Describe what you see with type 1 BVDV

Answer 3

reduced repro performance
immunosuppression
mild systemic illness

Question 4

When is mucosal disease seen

Answer 4

end stage of PI life

Question 5

what is seen with type 2 BVDV

Answer 5

generally severe disease often fatal, usually adults
thrombocytopenia, diarrhoea, haemorrhagic disease
RARE in UK

Question 6

How can BVDV virus increase resp disease in calves

Answer 6

Immunosupression
more likely for IBR +RSV and M. haemolytica infections

Question 7

What happens if non-pregnant cow gets infected with BVDV

Answer 7

transient infection

Question 8

When do antibodies show for non-pregnant cow gets infected with BVDV

Answer 8

from 2-4 weeks and persist for several years

Question 9

what happens if <120 days gestation cow gets infected with BVDV

Answer 9

death and reabsorption, abortion, mummification or stillbirth; if the fetus survives, then PI

Question 10

what happens if 120-190 days gestation cow gets infected with BVDV

Answer 10

stillbirth/abortion, abnormalities in calf

Question 11

what happens if 190+ days gestation cow gets infected with BVDV

Answer 11

normal calf

Question 12

List 5 possible outcomes of BVDV infection in pregnent animals

Answer 12

embryo loss
congenital defects
abortion
normal calf
PI calf

Question 13

How id PI calf created

Answer 13

BVDV crosses placenta before immune system- calf recognises it as normal so never generates antibodies

Question 14

T/F PI can only be caused by pregnant cow getting infected with BVD

Answer 14

False
All PI dam produce PI calves

Question 15

T/F all PI calves go on to show mucosal disease

Answer 15

False
may show no signs at all

Question 16

How long do PI calves shed BVDV for

Answer 16

their whole lives - and shed alot of virus

Question 17

Describe the signs of mucosal disease

Answer 17

weight loss
bloody D+
dehydration
ulcerative lesions in mouth and interdigital space

Fatal condition

Question 18

How does mucosal disease occur

Answer 18

Virus mutates from non-cytopathic to cytopathic form (ie cell killing form)- occurs in PI calves

Transmission of cp strain = potential for MD in other PIs

Question 19

T/F bulls can spread BVDV

Answer 19

True
can be PI or acutely infected

Question 20

How can a bull be blood Ab positive but antigen neg but still be PI

Answer 20

virus can ‘hide’ in testicles “immunological privileged site”
only identified by semen sample

Question 21

What is a good screening test for BVDV in dairy cows

Answer 21

Viral Ag can be detected in bulk milk, from 1 PI in 300 cows

Question 22

List 2 ways to look for BVDV in calves

Answer 22

blood Ag test pre-colostrum
ear tissue sample

Question 23

Presence of virus in samples can mean….

Answer 23

Animal is PI
animal is acutely infected- Viraemia following acute infection lasts up to 2 weeks

Question 24

Describe how to demonstrate a PI animal

Answer 24

2 positive antigen tests >3 weeks apart
Usually PIs have low/no antibody levels in both samples

Question 25

What should you do if you find a PI

Answer 25

KILL IT- because shed virus alot and can't treat

Question 26

what do you need to consider when testing a high number of cows for BVDV

Answer 26

Sensitivity and specificity of both Ab and Ag test rel. good BUT no test is perfect…

Question 27

Describe the Blood sampling heifer cohort method of BVDV herd monitoring

Answer 27

Blood sample for Ab from ~ 8 months of age (maternal Ab)- sample 8-10 from group should be Ab neg

Question 28

at what level on bulk milk BVDV test shows recent or active exposure

Answer 28

>0.7

Question 29

Describe the basic approach to BVD control

Answer 29

Evaluate current herd status Assess the routes by which virus could enter the herd and spread within the herd Eradication by removal of PIs and preventing new cases

Question 30

Describe how BVDV is spread

Answer 30

nose-to-nose contact main route PIs most important sources Faeces a poor source

Question 31

When do you vaccinate for BVD

Answer 31

must ensure protection before first breeding Lots of vaccines avaliable

Question 32

What is the best way to eradicate BVD and prevent re-infections

Answer 32

Vaccination and monitor for PIs

Question 33

When can do nothing approach to BVD work

Answer 33

If the herd only monitor through bulk milk Ab and are consistently low/medium positive, this is still a fairly common option But probably lots of hidden coats

Question 34

Is BVD zoonotic

Answer 34

No

Question 35

What is the main clinical sign of Bovine viral diarrhoea virus ? 1 - Dyspnoea 2 - Abortion 3 - Diarrhoea 4 - Conjunctivitis

Answer 35

2- Abortion

Question 36

Which of these is not a transmission route for BVD ? 1 - Feco-oral 2 - In-utero 3 - Milk 4 - Venereal 5 - Saliva

Answer 36

3- Milk

Question 37

Which serotype of BVDV is most common in the UK ? 1 - BVDV type 1 2 - BVDV type 2

Answer 37

1- BVDV type 1

Question 38

T/F The cytopathic form of BVDV can be transmitted to other cattle

Answer 38

False limited to PI calves

Question 39

Bulls can be PI animals and so can be a major spread for disease in BVDV. What is the rarer form that bulls can get in which they can transmit to the to the herd ? Virus resides in 1 - Brain 2 - Lungs 3 - Testicles 4 - Lymph nodes

Answer 39

3

Question 40

Which of these is an appropriate way of testing for BVDv on an individual basis ? 1 - Fecal PCR 2 - Blood ELISA 3 - Fecal ELISA 4 - Bulk milk tank ELISA

Answer 40

2

Question 41

What can alter testing results sensitivity when testing for PI calves ?

Answer 41

colostrum

Question 42

What is needed in order to diagnose a PI calf ? 1 - 1 x positive antigen and negative antibody test 2 - 2 x positive antigen and negative antibody tests (3 weeks apart) 3 - 2 x negative antibody tests (3 weeks apart) 4 - 2 x positive antigen tests (3 weeks apart)

Answer 42

2

Question 43

In order to sample youngstock for presence of PI calves we need to do it before colostrum is given or after at what age ? 1 - >1 month 2 - >2 months 3 - >4 months 4 - >8 months

Answer 43

4- 8 months