African swine fever virus (ASFV) causes a devastating disease of pigs. It is a large complex DNA virus and is the only member of the Asfarviridae family, genus Asfivirus. ASFV has several layers that surround a dense core containing its DNA genome. The image shows virus particles at different stages of assembly.
See the news feature on ASF to learn more about the disease and how you can help protect the UK's pigs.
- African swine fever is a notifiable disease and should be reported.
Please see the Defra website for advice on how to spot and report the disease. Guidance to pig keepers on preventing the disease is also available.
African swine fever expert, Dr Linda Dixon, explains what ASF is and how it is spread in a BBC World Service Science in Action interview.
African swine fever virus (ASFV) causes a severe disease in domestic pigs and wild boar that can result in death in almost all pigs that are infected. There is currently no treatment or vaccine available and therefore biosecurity measures are essential to prevent an outbreak from spreading.The clinical signs of ASF can vary but are similar to some other pig diseases. Signs typically occur 3-15 days after-infection.
The early signs are non-specific and include:
- High fever, lethargy and loss of appetite.
- Pigs may die suddenly without further disease signs.
At later stages further signs may be observed including:
- Reddening of the skin (visible only in pale-skinned pigs), with patches appearing on the tips of ears, tail, feet, chest, or under the belly.
- Diarrhoea, vomiting.
- Laboured breathing.
- Swollen red eyes, eye discharge.
- Abortions, still-births.
- Increasing morbidity and unwillingness to get up.
In severe cases death can sometimes be the only sign of infection, with a case fatality rate as high as 100%.
Images of ASF clinical signs:
Pictures copyright The Pirbright Institute.
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The disease can be spread directly through contact. It can also be spread indirectly through feeding infected pig meat and /or pork products, species of soft tick in some regions and possibly blood sucking flies or insects and through contaminated objects (fomites) such as vehicles, clothes, equipment etc.
Since emerging in the early 1900s from East Africa, ASF has moved through sub-Saharan Africa and on two occasions has entered European countries. Since the second incursion to Georgia in 2007, ASF continued to the Russian Federation and Eastern Europe, including EU countries in the Baltic States, Poland, the Czech Republic, Hungary, Romania. In August 2018, Bulgaria and China confirmed outbreaks, shortly followed by Belgium in September. The disease continues to spread, and has now reached many more countries in Asia. For up to date information on the location of ASF outbreaks, visit the World Organisation of Animal Health Information Database.
Impact for Society – what are we doing?
Scientists at The Pirbright Institute have been working on understanding the virus since 1963, prior to its spread to Europe and Asia from Africa, and is one of the few institutes that continues to have an ASF research programme.
Pirbright researchers are currently developing different types of ASF vaccines (a live attenuated vaccine and a subunit vaccine) with the aim of producing one that will protect pigs from this deadly disease. They are also working with ViroVet to produce ASF antivirals that could lower virus replication in pigs and limit clinical signs, which would form an important part of any feed-based strategy to control the virus.
As the World Organisation for Animal Health (OIE) Reference Laboratory for ASF, Pirbright provides surveillance and diagnosis of ASF globally and continually works towards improving tests to detect the virus. Pirbright experts also provide advice to Department for Envionment, Food and Rural Affairs (Defra) and OIE, and have helped to provide resources for vets that will help them to identify ASF quickly should it ever present in the UK.