African Swine Fever

ASF = African Swine Fever, ASP = Afrikanische Schweinepest

Changed on: 18.01.2021
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Transmission of African swine fever

African swine fever is a highly contagious animal disease of wild and domestic pigs. African swine fever does not cause disease in humans. However, travellers coming from areas with African swine fever can transmit the disease.

The disease is caused by a virus, there is no vaccine. It is deadly for domestic pigs and wild boars. The virus can remain contagious in blood, meat, bones and food for months and can be transmitted via contaminated shoes, clothing, tools and containers. There is no risk of infection for other domestic animals and humans.

Be aware of the following measures:

  • It is forbidden to bring meat, sausages, bacon etc. from non-EU countries into European Union countries. Do not bring any food made from pork or wild boar meat from domestic slaughter
  • Dispose meat and sausage leftovers into lockable waste containers
  • Feeding of food scraps to domestic and wild pigs is prohibited
  • Avoid any contact with domestic and wild boars as far as possible

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.

Situation in Austria

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


Legende

    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

    Year ASF-Antibody ASFV PCR
    2011 0 0
    2012 0 5
    2013 0 5
    2014 0 10
    2015 0 13
    2016 0 9
    2017 0 8
    2018 0 5
    2019 0 11

    Table 3: ASF examinations wild boar

    Year ASP-Antibody ASPV PCR
    2011 223 298
    2012 43 2
    2013 32 2
    2014 0 98
    2015 0 74
    2016 0 45
    2017 0 68
    2018 0 152
    2019 0 177

    Situation in Europa

    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

    Professional information

    Veterinary Medicine

    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

    Mode of transmission

    The transmission path via ticks of the genus Ornithodoros, which is important in Africa and historically also in Europe, does not play a role in Europe according to current knowledge. Domestic pigs and wild boars become infected through contact with infected conspecifics, ingestion of virus-containing food waste and possibly via contaminated objects such as agricultural implements, vehicles and clothing.

    Infographics Transmission routes (PDF)

    Symptoms

    The incubation period is 4-19 days. The main symptoms are fever (40.5 °C to 42 °C) and apathy. After the pathogen has entered the host, the first symptom is viremia with fever.

    Many African wild boars (e.g. warthogs) are inapparently infected with the virus. Pigs can carry the virus even without clinical symptoms (asymptomatic carriers). Pigs with symptoms show typical clinical signs depending on the strain of the virus. There are several forms of progression - depending on the virulence of the pathogen:

    Peracute - acute form (usually caused by highly virulent ASFV strains)

    • Fever (40.5 °C to 42 °C)
    • Leukopenia and thrombocytopenia (48 to 72 hours)
    • Erythema = skin redness: ears, tail, distal extremities, abdomen and chest
    • Bleeding in internal organs (spleen, lymph nodes, stomach, kidneys, lungs)
    • Increased pulse frequency
    • Increased breathing frequency
    • Vomiting
    • Diarrhoea (mostly also bloody)

    Death occurs within 6-13 days (up to 20 days). The mortality rate for domestic and wild pigs is 90-100%.

    Subacute form (usually caused by moderately virulent ASFV strains)

    Symptoms are not as pronounced as in the acute form; abortions occur more frequently. The course of the disease lasts 5-30 days. Death occurs within 15-45 days. The mortality rate is lower than for the acute form (30-70%).

    Chronic form (usually caused by low-virulent ASFV strains)

    Symptoms are not as severe as in the acute form

    • Weight loss
    • Irregular temperature fluctuations
    • Respiratory problems
    • Arthritis
    • Chronic skin ulcers, partly skin necroses
    • Pericarditis
    • Lung adhesion
    • Swollen joints
    • The course of the disease lasts about 2-15 months
    • Low mortality rate (< 20 %)

    Diagnostics

    • Testing for antibodies from blood (serum) by ELISA or immune peroxidase test. The result shows if the animal has had contact with the virus. The detection of antibodies does not mean immunity. In the peracute to acute form, the animals usually die before they develop antibodies
    • Examination by PCR from blood (EDTA blood) and organs (spleen, tonsils, lung, kidney, liver, lymph nodes, bone marrow), as well as abortion material. Swabs containing blood are also suitable for virus detection. PCR detects the virus or virus components directly
    • Virus isolation: in contrast to PCR, this method shows whether the virus is capable of infection. Virus isolation is hardly used in routine diagnostics

    In all cases, samples should be shipped to the laboratory (see contact), ideally with the addition of coolants and taking into account the relevant transport regulations (UN3373), by an authorised logistics company.

    Contact, forms

    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

    Downloads

      Informationsblatt für Saisonarbeiter bulgarisch (740 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter deutsch (654 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter polnisch (743 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter rumänisch (739 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter russisch (741 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter serbisch (775 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter slowakisch (746 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter tschechisch (745 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter ukrainisch (742 K)
      Afrikanische Schweinepest
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      Informationsblatt für Saisonarbeiter ungarisch (747 K)
      Afrikanische Schweinepest
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