African Swine Fever (Animal)
Primary reference(s)
FAO, OiE, and EC, 2019. African Swine Fever in Wild Boar Ecology and Biosecurity. Food and Agriculture Organization of the United Nations (FAO), World Organisation for Animal Health (OiE), European Commission (EC). Accessed 4 October 2020.
Additional scientific description
African Swine Fever (ASF) is a highly contagious, generalised disease of pigs caused by an Iridovirus of family Asfarviridae that exhibits varying virulence between strains and is very hardy to physical and chemical inactivation. The agent can remain viable for long periods in blood, faeces and tissues. It can also multiply in its vectors. In view of this, control of ASF is dependent on stamping-out policy and strict quarantine enforcement. It most commonly appears in the acute form as a haemorrhagic fever. Subacute and chronic forms of the disease also exist. Mortality is usually close to 100% and pigs of all ages are affected (FAO, 2019).
The causative agent of ASF is a unique, enveloped, cytoplasmic, double-stranded DNA arbovirus, which is the sole member of the family Asfarviridae. Although it was generally considered that there is only one serotype of ASF virus, recent studies have reported the classification of 32 African Swine Fever virus (ASFV) isolates in eight different serogroups based on a hemadsorption inhibition assay (FAO, 2019).
In the natural sylvatic cycle, the soft-bodied, eyeless Ornithodoros ticks (also known as tampans) are, together with African wild suids, the natural reservoir hosts of ASFV. They can transmit the virus through their bites. All members of the pig family (Suidae) are susceptible to infection, but clinical disease is only seen in domestic and feral pigs, as well as in the closely related European wild boar. Wild African suids are asymptomatic carriers of ASF and act as the reservoir of the virus in parts of Africa. These include warthogs (Phacochoerus africanus and P. aethiopicus), bushpigs (Potamochoerus porcus and P. larvatus) and giant forest hogs (Hylochoerus meinertzhageni) (FAO, 2019).
In domestic pigs, ASF is transmitted mainly through direct contact, via the oronasal route, through excretions from infected pigs, or from ingestion of pork or other contaminated products containing the virus (e.g., swill, waste, carcasses, etc.). Further transmission pathways are indirect contact through fomites or vector-borne transmission through bites from infected Ornithodoros soft ticks, where present.
ASF is present in wild and/or domestic pigs in regions of Asia, Europe and Africa (OIE, 2018). People can transport the virus over large distances through contaminated meat and other sub-products such as skins, skulls, tusks or other hunting trophies (OIE, 2018; FAO, OIE and EC, 2019).
The disease is not a zoonosis, i.e. it does not infect humans.
Metrics and numeric limits
Not found.
Key relevant UN convention / multilateral treaty
WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) (WTO, 1994).
WTO and the World Organization for Animal Health (OIE) (WTO, 1998).
UN Recommendations on the Transport of Dangerous Goods - UN Model Regulations Model Regulations Nature, Purpose and Significance of the Recommendations (UNECE, no date).
Examples of drivers, outcomes and risk management
Drivers: lack of biosecurity, swill feeding and transport of live pigs and uncooked port products, presence of the competent vector ticks of the genus Ornithodorous.
Outcomes: death of infected animals, spread of infection and trade ban. The disease is the cause of major economic losses, threatens food security and safe trade, and challenges sustained swine production in affected countries.
Risk management: depopulate infected herd, movement control, improve biosecurity at farms.
Recommendations for countries with ASF (FAO, 2019):
- Prioritise animal disease containment in its broadest sense within the highest levels of government.
- Ensure and enhance preparedness capacities (e.g., contingency planning, standard operating procedures (SoPs), secured financial support) based on the principles of early warning, detection and notification, early reaction/action, and coordination. These need to be reviewed periodically in relation to changing disease situation.
- Apply strict biosecurity measures; frequently clean and disinfect farms and transport vehicles; and improve husbandry practices and production systems.
- Strengthen surveillance and monitor transport of live pigs as well as pork products.
- Good communication and coordination with the swine-producing commercial sector and swine famers are essential to strengthen cooperation in ASF prevention, detection, and control. Ensure awareness and training of all stakeholders, from veterinarians to farmers, intermediaries and other value chain actors.
- Ensure means to communicate to the public are place to avoid rumours leading to food safety perceptions and consumption disruption.
- Farm registries, animal identification and censuses are essential for locating animals in the event of outbreaks and animal health interventions.
- Prohibit swill feeding.
- Strengthen proper disposal of food waste (food services, airports, seaports), which may contain uncooked pork products.
- Put in place sustainable outbreak control strategies. These need to be developed in consultation with the private sector (pig production and allied industries, such as transport, feed operators), which should be actively involved in disease management options.
Recommendations for National Considerations, Inter-Regional Collaboration and Solidarity (FAO, 2019):
- Strengthen intraregional networks on disease management and diagnostic protocols.
- Understanding of pig and pork value chains within the country and with neighbouring countries is essential for improved risk management.
The World organization for Animal Health (OiE) has published the Terrestrial Animal Code with guidance for Infection with African swine fever virus (OIE, 2019)
References
FAO, 2019. African Swine Fever Virology. Food and Agriculture Organization of the United Nations (FAO). Accessed 10 October 2020.
FAO, OiE, and EC, 2019. African Swine Fever in Wild Boar Ecology and Biosecurity. Food and Agriculture Organization of the United Nations (FAO), World Organisation for Animal Health (OiE), European Commission (EC). African Swine Fever Virology. Food and Agriculture Organization of the United Nations (FAO). Accessed 10 October 2020.
OIE, 2018. African Swine Fever. World Organisation for Animal Health (OIE). Accessed 10 October 2020.
OIE, 2019. Terrestrial Animal Health Code. Chapter 15 Infection with African swine fever virus. World Organisation for Animal Health (OIE). Accessed 10 October 2020.
UNECE, no date. UN Recommendations on the Transport of Dangerous Goods - UN Model Regulations Model Regulations Nature, Purpose and Significance of the Recommendations. United Nations Economic Commission for Europe (UNECE). Accessed 3 October 2020.
WTO, 1994. The WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement). World Trade Organization (WTO). Accessed 9 October 2020.
WTO, 1998. The World Trade Organization (WTO) and the World Organization for Animal Health (OIE). G/SPS/GEN/775. Accessed 9 October 2020.