African swine fever virus

African swine fever virus (ASFV) causes an economically important 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 how the disease is spreading. 

  • 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.

Associated diseases:

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. 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%. 

Disease transmission:

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.

Disease prevalence:

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 Vietnam and most recently Cambodia in April 2019.

Impact for Society – what are we doing?

There is currently no treatment or vaccine available and therefore biosecurity measures are essential to prevent an outbreak from spreading.

By researching ASFV, our scientists hope to gain a better understanding of how the virus works and use this information to produce vaccines. They are specifically working on finding the genes that are involved in lowering the immune systems response. Research is ongoing to delete these genes so that the modified virus can then be used as a vaccine. Alternatively, the proteins of the virus are being screened to find which would be best at creating a protective immune response.


Downloadable factsheet

Clinical signs of ASFV infection

Pictures copyright The Pirbright Institute. For use of these images please email

Research papers

Dixon L K, Sun H, Roberts H (2019)

Antiviral Research 165 , 34-41
Dixon L K, Islam M, Nash R, Reis A L (2019)

Virus Research 266 , 25-33
Mulumba-Mfumu L K, Saegerman C, Dixon L K, Madimba K C, Kazadi E, Mukalakata N T, Oura C A L, Chenais E, Masembe C, Stahl K, Thiry E, Penrith M L (2019)

Transboundary and Emerging Diseases 66 (4) , 1462-1480
Publisher’s version:
Netherton C L, Goatley L C, Reis A L, Portugal R, Nash R H, Morgan S B, Gault L, Nieto R, Norlin V, Gallardo C, Ho C-S, Sánchez-Cordón P J, Taylor G, Dixon L K (2019)

Frontiers in Immunology 10 , 1318
Netherton C L, Connell S, Benfield C T O, Dixon L K (2019)

Frontiers in Genetics 10 , 402


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