Bovine Viral Diarrhoea (BVD)
Bovine viral diarrhoea (BVD) is an endemic viral disease of cattle. Infection of cattle with BVD can cause a wide range of health problems such as abortion, infertility, respiratory and gastro-intestinal disorders.
The disease is mainly spread by a small population of persistently infected (PI) cattle. PI cattle are infected by their mothers in the uterus while their immune systems are immature, allowing them to become immunologically tolerant to the virus. As a result, PI cattle remain infected and continue to spread the virus for the rest of their lives.
Due to its significant economic and welfare implications, the Scottish cattle industry, supported by Scottish Government, embarked upon an ambitious Bovine Viral Diarrhoea (BVD) eradication programme in 2010. There is now also an official scheme in Northern Ireland and voluntarily schemes in Wales and England.
The following short animation includes summary information on the importance of biosecurity in preventing the transmission of bovine viral diarrhoea virus:
- Bovine viral diarrhoea (BVD) is a contagious disease of cattle occurring worldwide and many livestock farmers rate it among their highest economic and welfare concerns.
- BVD is caused by a pestivirus, bovine viral diarrhoea virus (BVDV), which causes a range of clinical outcomes, including infertility and reproductive problems, respiratory and gut disease and in some cases fatal mucosal disease.
- BVDV infection also induces immunosuppression, increasing the frequency of illnesses such as pneumonia and scour – most often in young stock.
- BVDV infection of non-pregnant cattle generally leads to a short illness, with fever occurring about a week after infection, followed by development of immunity characterised by the appearance of virus-specific antibodies.
- There are two main types of BVDV (type 1 and type 2) and multiple subtypes of each. Sometimes a particularly virulent strain of BVDV can cause severe illness or death. In the UK BVDV type 1 is prevalent and type 2 is rare.
- BVDV infection early in pregnancy can cause foetal death, presenting as infertility or ‘repeat breeding’. Infection in mid-pregnancy may lead to abortion or stillbirth. Infection late in pregnancy can lead to birth of uninfected, BVDV-immune calves. Early BVDV-infected foetuses that survive to term are born persistently infected (PI) with the virus: they tolerate it without developing an immune response. Infection affects multiple tissues and all PI calves shed the virus continuously. PI calves can show poor growth but many appear normal. Maternal antibodies may initially mask the presence of infectious virus.
- PI calves excrete virus for the rest of their lives and may develop mucosal disease (a fatal enteric disease) at any age. If a PI cow breeds successfully she will always produce PI calves.
- BVDV infection is spread and maintained mainly through the virus excreted by PI animals. They will rapidly infect cattle that are in close contact and can also infect other animals indirectly.
- Non-PI cattle can be transiently infected but cannot become persistently infected.
- Bulls infected with the virus may become infertile for several months and can transmit the virus to susceptible cows in their semen.
- Control and prevention of the infection can be achieved by applying strict biosecurity procedures, vaccination and long-term control strategies. Several countries have successfully eradicated BVD.
- There is no national BVDV eradication scheme in the UK but official eradication schemes are active in both Scotland and Northern Ireland, while voluntary schemes are available in the rest of the UK
Research at Moredun is focused on understanding the diversity of BVDV viruses in the UK, with the potential to help us understand how new outbreaks of BVDV might occur at late stages in the eradication. Diagnostic samples from PI animals are being collected and the sequence of a short region of the BVDV genome is defined for each sample. Between 2012 and 2018, about 4000 samples were analysed (about two-thirds of these from Scotland) and illustrate the distribution of BVDV strains within the UK and provide a baseline dataset for analysis later in the eradication.
Moredun is contributing to the Scottish BVDV eradication scheme. The Scottish cattle industry, supported by Scottish Government, embarked upon a Bovine Viral Diarrhoea (BVD) eradication programme in 2010. The impact of this programme has been significant: over 90% of Scottish breeding holdings now have a negative BVD status.
The programme is based on the use of herd- and individual level diagnostic testing to assure herd and animal BVDV status, with restrictions on the movement of PI cattle and on movement from holdings which have a non-negative BVDV status.
Current interests and future aims:
- We are interested in looking at how the diversity of BVDV strains is changing during the eradication campaign in Scotland, using the analysis of virus sequences and collaborating with scientists within the EPIC centre of expertise (www.epicscotland.org.uk).
- We are also interested in developing methods to sequence entire BVDV genomes from small diagnostic samples to provide high-resolution strain identification and to understand how the virus may change within and between animals.
This work is funded by the Scottish Government via the RESAS Strategic Research Programme and the EPIC centre of expertise in animal disease outbreaks.
For further Information about BVD please see Moredun Newssheet 5.20 – Control of Bovine Viral Diarrhoea and Moredun Newssheet 6.10 – Biosecurity for Key Livestock Diseases:
- If you are a Moredun Member you can view this online by signing in to the Member Portal
- For non-members you can request a copy by contacting The Moredun Communications Team
For information about the eradication schemes currently operating in the UK please follow the links to the relevant websites below:
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