BVD – the disease, the veterinarian and the control strategies Joe Brownlie © 2008 Royal Veterinary College

BVD Disease …….and the Vet! European Dimension Control, Vaccination & Eradication Joe Brownlie © 2008 Royal Veterinary College

Pieces that need to be in place.. Education Veterinary motivation Joe Brownlie © 2008 Royal Veterinary College

The Vet was the main source of information on infectious disease. The press was also a key source of information Q9 What are your sources of information on infectious diseases in cattle. Let's start with your main source? CODE ONE ONLY. And where else? Base All respondents (679) 79% 55% 12% Joe Brownlie © 2008 Royal Veterinary College

BVD was the main threat to herds – VETS (especially according to vet assistants (87%) ) Q11 Which infectious diseases OF CATTLE do you feel are the biggest threat to herds under your care. Lets take the main threat first, then the second etc. Base All respondents (93) 79% 37% 34% Vet assistants: 87% Joe Brownlie © 2008 Royal Veterinary College

Pieces that need to be in place.. Education Motivation Veterinary motivation Joe Brownlie © 2008 Royal Veterinary College

2/3 of VETS were actively promoting BVD control; 1/3 were not! Q24 Which of the following BEST reflects your approach to BVD? Base All respondents (93) Vet partners more likely to actively promote BVD control (74%) than assistants (63%) Joe Brownlie © 2008 Royal Veterinary College

Reproductive disease Classical swine fever virus (Hog cholera virus) Bovine virus diarrhoea virus Border disease virus non-cytopathogenic virus (except mucosal disease) crosses placenta foetal infection congenital damage abortion Joe Brownlie © 2008 Royal Veterinary College

Group 1 BVDV nc - mild disease >90% UK herds - virus clearance days - antibody responses slow 10 – 12 weeks - antibodies cross-protective to other BVDV isolates ACUTE INFECTION Joe Brownlie © 2008 Royal Veterinary College

BVDV - immunosuppressive with mixed infections Respiratory infections Worse with BVDV! BVDV+other viruses (IBR+RSV) +bacteria (P. Haemolytica) Enteric infections Worse with BVDV! BVDV+other viruses (corona & rota) +bacteria (Salmonella etc)

Severe Haemorrhagic Syndrome Thrombocytopenia in acute infections field:- (Perdrizet et al, 1987 Cornell Vet Rebhun et al, 1989 J Vet Int Med) experimental:- (Corapi et al, 1989 J Virology) Acute fatal diseases in adult cattle (Hibberd et al 1993 Vet Record David et al 1993 Vet Record) Joe Brownlie © 2008 Royal Veterinary College

Group 2 BVDV nc - severe disease often fatal - virus clearance 28 – 38 days - thrombocytopenia, diarrhoea, haemorrhagic disease - weak cross-protection to Group 1 BVDV antibodies - distinct 5 UTR clustering ACUTE INFECTION Joe Brownlie © 2008 Royal Veterinary College

Reproductive disease Joe Brownlie © 2008 Royal Veterinary College

Infection of the pregnant dam Early pregnancy (up to 110 days) early foetal loss, congenital loss, persistently infected animals Joe Brownlie © 2008 Royal Veterinary College

BVDV reproductive disease BVD Stillbirths Abortions/mummified foetus PI calves Joe Brownlie © 2008 Royal Veterinary College

BVDV in early pregnancy Cow and calf infected Only dam becomes immune Calf born persistently infected (PI) Birth of a PI calf Joe Brownlie © 2008 Royal Veterinary College

PI animals Early pregnancy (up to 110 days) early foetal loss, persistently infected animals 1-2% of national population are PI animals However may be much higher in foetal calves (up to 13%) (Nettleton 1985) Joe Brownlie © 2008 Royal Veterinary College

the Holsteins go on Holiday Transmission pathways PI dams to early foetal calf 100% Acute infection to PI calf ? Joe Brownlie © 2008 Royal Veterinary College

the Holsteins go on Holiday Likely transmission pathways to PI? PI dams to PI calf 7 % Acute infection to PI calf 93% Joe Brownlie © 2008 Royal Veterinary College

BVDV: Effects on Reproduction Infection during early pregnancy (Day 1-24) Embryonic Mortality Expt 1 22% conception in infected heifer 79% conception in uninfected heifers (Virakul 1988) Expt 2 33% pregnancy rate in infected cattle 79% pregnancy rate in un-infected cattle (McGowan 1993) Joe Brownlie © 2008 Royal Veterinary College

The Bull Can be PI Can be acutely infected Cumulus bull ALWAYS TEST THEM Joe Brownlie © 2008 Royal Veterinary College

Pieces that need to be in place.. Education Good diagnostics Motivation Veterinary motivation Joe Brownlie © 2008 Royal Veterinary College

Mucosal Disease A fatal disease of cattle, usually between months, associated with BVDv (?) Joe Brownlie © 2008 Royal Veterinary College

60% of these cattle were PI and all the PI animals died of Mucosal disease Joe Brownlie © 2008 Royal Veterinary College

Normal bovine intestinal lymphoid tissue MD Discrete Peyers patch Continuous Peyers patch ileum Joe Brownlie © 2008 Royal Veterinary College

Intestinal lymphoid depletion MD necrosis Joe Brownlie © 2008 Royal Veterinary College

BVDV NON-CYTOPATHOGENIC CYTOPATHOGENIC Two biotypes Joe Brownlie © 2008 Royal Veterinary College

VIRUS-ve +ve nc +ve nc+c ANTIBODY-ve+ve-ve STATUSnaïveimmunePI MD Joe Brownlie © 2008 Royal Veterinary College

BVDV in early pregnancy Cow and calf infected Only dam becomes immune Calf born persistently infected (PI) Fatal Mucosal disease Mucosal Disease Superinfection with second BVDV biotype Joe Brownlie © 2008 Royal Veterinary College

What is happening in Europe? Joe Brownlie © 2008 Royal Veterinary College

NationalRegional Joe Brownlie © 2008 Royal Veterinary College

Sufficient resources Pieces that need to be in place.. Education Good diagnostics Motivation Veterinary motivation Joe Brownlie © 2008 Royal Veterinary College

Separation between non-infected- and infected herds using herd level diagnostics BULK MILK BULK MILK Joe Brownlie © 2008 Royal Veterinary College

Screening/monitoring methods BULK MILK BULK MILK (7) 12 months Strategy in non-infected herds Joe Brownlie © 2008 Royal Veterinary College

BVD Virus V A C C I N E Measles Joe Brownlie © 2008 Royal Veterinary College

Vaccination was a key factor in the control & prevention of infectious disease - VETS Q15 What if any steps do you take to control and prevent infectious diseases on farms under your care? Base All respondents (93) South (49) = SE, SW, Wales, W Mids, E Mids, Eastern; North (44) = Scotland, NE, NW, Yorks Vaccination more likely in South 86% (North 68%)

Non-Systematic Approach Involving Vaccination What can 40 years of vaccination and 160 currently licensed vaccines* do to eradicate a disease? When you are talking about bovine viral diarrhea virus, apparently not much it is still thriving. *in the USA ** J. Ridpath, 2002: Although applied almost world-wide, just unsystematically vaccinating cattle does not even influence the high incidence of BVDV infections Joe Brownlie © 2008 Royal Veterinary College

Sufficient resources Pieces that need to be in place.. Education Good diagnostics Ownership strategy Motivation Veterinary motivation Joe Brownlie © 2008 Royal Veterinary College

Is there a UK national strategy? Joe Brownlie © 2008 Royal Veterinary College

Is there a UK national strategy? National initiative to prepare a National Strategy BVD Control Strategy Group Wide representation from industry, veterinary profession (BCVA), academia & government Pilot BVD Eradication programmes underway Joe Brownlie © 2008 Royal Veterinary College

BVD Control Options GB Do Nothing Vaccinate Control PI calves Control PI calves & Vaccinate Joe Brownlie © 2008 Royal Veterinary College