African Swine Fever

Occurrence

The origin of African swine fever is in Africa, where the virus also shows the highest genetic diversity. From there, it spread several times to Europe and Asia in the course of food transports.

Reservoir

In Africa, different types of pigs (bush pigs, forest pigs and warthogs), as well as ticks of the genus Ornithodoros are the main reservoir of pathogens. In Europe, wild boar serves as the main reservoir of the virus.

Mode of transmission

Pigs and boar become infected by the bite of infected ticks (currently this transmission route is not important in Europe), by direct contact of susceptible (wild) pigs with infected conspecifics, or via ingestion of virus-containing food waste. The virus is very resistant, it remains partly infectious even after drying or processing/maturing in raw meat products such as raw ham or salami.

Incubation period

4 to 19 days

Symptoms

The symptoms are strongly dependent on the strain of the virus. The strain currently present in Europe, known as genotype 2, usually leads to high fever, severe general illness in domestic and wild pigs of all ages, and can cause bleeding into the skin and internal organs. Affected animals usually die of the disease before they develop antibodies. However, there are also other virus strains that lead to milder disease progression.

Treatment

There is no treatment for the ASF virus.

Preventive measures

Although a vaccination against ASF is being worked on, it is not yet available. Prevention is therefore limited to early detection, separation and eradication of infected animals.

Austria has so far been spared from African swine fever, although it does occur in some direct neighbouring countries such as Germany, Slovakia, the Czech Republic and Hungary. In Austria, since the end of 2019, all feral pigs found dead must be reported and examined by AGES for the ASF virus for the purpose of early detection. In addition, an examination of abortions as well as of clinically or pathologically conspicuous domestic pigs is also carried out.

Figure 1: Surveillance of domestic and wild pigs

In 2019, 2,106 domestic pigs (including farmed game) were officially examined, only a fraction of which were in the course of exclusion examinations (Table 2) In the same year, 177 wild boars were examined for ASF virus (Table 3). In none of these cases the virus was detected.

Table 2: ASF exclusion examinations of domestic pigs

In early 2014, cases of African swine fever were detected for the first time in the EU in feral pigs in Poland, Lithuania, Latvia and Estonia. African swine fever in feral and domestic pigs has also been detected in other European countries (Germany, Belgium, Bulgaria, Moldova, Romania, Russia, Serbia, Slovakia, Czech Republic, Ukraine, Hungary).

Ministry of Health: Current information on the disease situation in Europe

African swine fever virus (ASFV) is a DNA virus, the only virus belonging to the family Asfarviridae, genus Asfivirus. The ASFV has a double-stranded DNA genome with a very complex structure, which is approximately 170,000 to 192,000 base pairs in size. There is only one serotype, but based on the viral p72 gene, 24 different genotypes are currently known. The virus shows tropism to macrophages and is therefore present in high quantities in blood and all blood-containing organs. ASF is a notifiable disease.

EFSA Journal 2018; 16(7):5344: African swine fever in wild boar

Lectures, documents, BTSF workshop, webinar on African swine fever, 19.9.2017

BMSGPK: Information for pig farmers

Landwirtschaftskammer Österreich: Biosafety /Pig Health Ordinance

Institute for Veterinary Investigations Mödling (national reference laboratory)

Robert Koch-Gasse 17
A-2340 Mödling

Tel: +43 50 555-38112
Fax: +43 50 555-38108

E-mail: vetmed.moedling@ages.at

Federal Ministry of Social Affairs, Health, Care and Consumer Protection: Information on legal bases and measures in Austria