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Bovine Viral Diarrhoea (BVD)

What is BVD?

Image of cattle

It is a disease of cattle caused by a pestivirus. In the UK, BVDV-1 is the most common virus, but BVDV-2 and Border disease virus (BDV) have also been found in cattle in recent years.  BVDV-2 is most commonly seen in North America, but also to a lesser extent in some central European countries.

Clinical signs

Acute infection with BVDV is usually subclinical and causes mild or inapparent disease. In dairy cows, it may result in a temporary drop in milk yield and/or scour. In calves, dual infections with respiratory or enteric pathogens, may produce a more severe clinical problem.

In some cases acute infection can result in a severe enteric disease syndrome and even mortality for adult animals. Reproductive losses can also be another sign of acute infection.

Persistent infection

If a naive pregnant animal is infected during the first three months of gestation, the foetus gets infected before its immune system is fully developed. If carried to term, the foetus may be born as a calf persistently infected (PI) with BVDV, and immunotolerant to the virus.

These PI animals may live to a mature age and are potent sources of virus to all their cohorts and are responsible for perpetuation of the virus in the cattle population. They may appear clinically normal or stunted and susceptible to other infections and are the only animals that can develop fatal mucosal disease.

Control of BVD

BVD is not a notifiable disease. However several countries have launched control programmes that are based on identification of PI animals for culling, with or without additional vaccination, to limit further virus circulation.

Several local BVD control schemes have also started in the UK.