Harmless to the native warthog and bush pig, but deadly to domesticated pigs. This virus causes red blood cells to disintegrate. It can be transmitted from pig to pig or by ticks that can carry the virus.
African swine fever (ASF) is a highly infectious disease that causes a large number of infected pigs to become ill very quickly and die. Pigs infected with the virus can show a wide range of symptoms, including fever, skin blotching, anorexia and diarrhoea. There is no treatment for this disease, and at present there is also no vaccine.
The ASF virus is injected into the pig by ticks while they feeds on the pig's blood. Once in the blood the virus seeks out a particular type of cell, which is part of the immune system (a macrophage). It then hi-jacks the cells machinery to produce the components needed for making new virus particles. Thus the macrophage becomes a virus factory.
The virus that causes African swine fever (ASF) belongs to a group of viruses called the Asfarviridae, which are related to Poxviruses - including smallpox - and Iridoviruses.
Blood-suckers
Ornithodoros ticks can carry several serious blood diseases that can affect both animals and humans.Ornithodoros moubata is the species that carries the ASF virus. Whilst its preferred host, the wart hog, is unaffected by the virus, the domesticated pig is highly susceptible.
Ornithodoros moubata usually lives in the burrows made by the wart hog, where it relies on the wart hog for its blood meals. However, it is also able to feed on domesticated pigs that may be in the area and hence passes on the infection that would otherwise go unnoticed. The virus can then be spread directly to other pigs.
New infections in the tick are established when it takes a blood meal from an infected pig or warthog. Once infective virus is made, in the salivary glands of the tick, the next round of infection is ready to start: tick > pig > tick >pig >...etc; it can also go tick > pig > pig > pig or even pig > pig > pig > pig.
Sardinia is the only part of the European Union where African swine fever occurs. An eradication programme is in force. ASF spread to several countries in the Caucasus in 2007. Disease has been confirmed in domestic pigs in Georgia, Armenia, Abkhazia Autonomous Republic, Southern Osetia, Nagoro-Karabayh and from wild boar in Chechnya.
To learn about some of the work undertaken on African swine fever at the Institute for Animal Health please visit the web pages of the African swine fever virus, Arbovirology and Vaccinology research groups.