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Disease factsheet: African Swine Fever

If you suspect signs of any notifiable disease, you must immediately notify a Defra Divisional Veterinary Manager.

6 June 2007 - Preliminary Outbreak Assessment: African Swine Fever - Georgia

Definition

African swine fever (ASF) is a highly contagious viral disease of pigs. Some strains of the virus cause severe disease and high mortality. Ornithodoros ticks, where present, can act as vectors of the ASF virus. ASF is clinically indistinguishable from Classical Swine Fever (CSF)

History and extent of the disease

African swine fever was first recorded in Kenya in 1921 and is present in most sub-Saharan African countries. It spread to southern Europe in 1957 but has persisted only in Sardinia (Italy). There have been no reported outbreaks of ASF in other European countries since the outbreak in 1999 in Portugal. Unlike Classical Swine Fever (CSF), this disease has never been recorded in the United Kingdom.

Clinical signs

The symptoms of ASF and CSF are very similar and either disease may occur in acute, sub-acute or chronic forms. Laboratory diagnosis is necessary to distinguish ASF from CSF. The essential differences between ASF and CSF are that ASF generally has a longer incubation period, it is possible for ASF to be transmitted by ticks, and the lack of any vaccine to control ASF. The incubation period for the ASF virus is variable but is usually between five and fifteen days. In the acute form pigs develop a high temperature (40.5 °C / 105 °F), become dull and go off their food. Other symptoms seen are variable but will include some or all of the following:

  • Vomiting
  • Diarrhoea (sometimes bloody)
  • Reddening or darkening of the skin, particularly ears and snout
  • Gummed-up eyes
  • Laboured breathing and coughing
  • Abortion, still births and weak litters
  • Weakness and unwillingness to stand

Differential diagnosis

  • Classical swine fever
  • Erysipelas
  • Salmonellosis
  • Pasteurellosis
  • All septicaemic conditions

Photos of clinical signs.

How could this disease be introduced and spread?

The main risk of ASF introduction is via infected pigmeat or pigmeat products, for example illegally imported pigmeat or bush meat from infected countries or legally imported meat from areas with undetected infection. The ASF virus can survive for many months in raw unprocessed frozen meats.

The disease could also be introduced through imported infected animals. The movement of infected pigs is a common method of spreading ASF. Apparently healthy pigs may be incubating disease and recovered pigs can excrete the virus for long periods of time.

The virus can survive outside the pig for a long time, so the movement of contaminated vehicles, clothing, footwear and equipment can also spread disease.

The ticks (Ornithodoros spp) that may spread the disease in other countries are not present in the UK.

What steps are taken to prevent this disease reaching Great Britain?

Great Britain operates strict controls over the import of animals and animal products primarily to guard against the introduction of animal diseases. While these methods are generally effective, it is possible that pigmeat infected with ASF virus may accidentally enter the country.

If the ASF virus does enter the country, the risk of it infecting pigs has been reduced by the ban on swill feeding introduced in May 2001 (now included in the Animal By-Products Regulations 2003). Should a pig become infected the spread of the disease would be limited by the controls contained in the Pigs (Records, Identification and Movement) Order 2003 (PRIMO). Further information on pigs identification and tracing can be found on our identification and tracing pages.

PRIMO also requires identification and movement recording control measures which provide invaluable aids in tracing contacts should a pig disease outbreak occur.

What can you do to guard your herd against this disease?

Watch your herd carefully for signs of disease. Wherever possible, purchase stock from known sources. Restrict the movement of persons, vehicles and equipment to and from your premises. When such movements are necessary disinfection facilities should be available and used. Provide a loading/unloading bay, which is solely for the use of incoming and outgoing stock. Follow the Defra Biosecurity guidance which is available.

What should you do if you suspect swine fever?

If you are the owner, person in charge or a veterinary surgeon attending pigs you must report your suspicions to the Defra Divisional Veterinary Manager at your local Animal Health Divisional Office. You must not move any pig, carcase or anything else (e.g. feed or waste) suspected of being infected with swine fever until a Defra veterinary inspector has visited and decided whether it is necessary to impose restrictions. If the veterinary inspector suspects the disease, movement restrictions will be enforced and material from the suspect animals will be sent for laboratory diagnosis to establish whether the condition is African or Classical swine fever, or neither. Samples are examined for both these diseases.

Legislation

Note: Unless otherwise stated any reference to swine fever in this section applies to both classical and African swine fever.

The Animal Health Act 1981 provides powers for the control of ASF.
Section 32(2) of the Animal Health Act, enables the Minister to apply slaughter procedures to any disease In the event of a suspect case, an appropriate Order would be made extending the powers of the Act to ASF.

The African Swine Fever (England) Order 2003, made under the Animal Health Act 1981, implements Council Directive 2001/60/EC for the control of African swine fever. In Scotland, the African Swine Fever (Scotland) Order 2003 applies, and in Wales the African Swine Fever (Wales) Order 2003 applies. The provisions of these Orders include the following measures:

  • Requirement for notification of suspicion of ASF.
  • Provision for a temporary control zone whilst the suspicion of disease on a premises is being investigated.
  • The imposition of movement restrictions and eradication measures at any premises on which there is a diseased or infected pig or carcase (an infected holding in the case of a farm).
  • Powers to make Declaratory Orders creating “infected areas”, comprising of a protection and surveillance zones surrounding an infected holding. Controls will be placed on the movements of pigs, manure, and any other pig by-products within the areas.
  • Cleansing and disinfection of buildings used to house pigs, their surroundings, the vehicles used for transport and all other things likely to be contaminated.

The Diseases of Animals (Seizure) Order, 1993 gives powers for the seizure and destruction of anything other than live animals that might carry or transmit the disease (including a carcase).

The African Swine Fever (Compensation) Order 1980, obliges the Minister to pay compensation for animals, which are infected or have been exposed to infection with ASF and which are slaughtered under the powers of the Animal Health Act 1981 referred to above . The basis for payment is the same as for CSF. A suitable provision would be made in the Order to update the 1980 Order.

Council Directive 2002/60/EC laying down specific provisions for the control of African swine fever and amending Directive 92/119/EEC as regards Teschen disease and African swine fever (OJ L. 192, 20.7.2002, p. 27) sets out measures required in EU law for the control and eradication of CSF in Member States. The key provisions of the Directive which domestic legislation implements are:

  • Notification to the competent authority of the Member State if ASF is suspected.
  • Imposition of movement controls on suspicion of disease.
  • Entry to premises for the purpose of veterinary inquiry.
  • Where disease is confirmed, the imposition of a PZ (minimum 3km) and a SZ (minimum 10km) around the infected holding.
  • Elimination of the disease by slaughter of infected and contact animals and/ or vaccination under strict controls.
  • Cleansing and disinfection of buildings used to house pigs, their surroundings, the vehicles used for transport and all equipment likely to be contaminated.
  • Surveillance of any feral pigs.

Disease Control Strategy

Note: Unless otherwise stated any reference to swine fever in this section applies to both classical and African swine fever.

The disease control strategy will be consistent with the UK’s EU obligations and in line with the appropriate EU legislation. The Government’s objective in tackling ASF will be to eradicate the disease and to restore the UK’s disease- free status as quickly as possible. In doing so, Government will seek to select control strategies which:

  • minimise the number of animals which need to be slaughtered, either to control the disease or on welfare grounds which keeps animal welfare problems to a minimum;
  • cause the least possible disruption to the food, farming and tourism industries, to visitors to the countryside, and to rural communities and the wider economy;
  • minimise damage to the environment and protecting public health; and
  • minimise the burden on taxpayers and the public at large

The control strategy adopted for African Swine Fever is similar to that used in Classical Swine Fever. This is due to the similarities in epidemiology and pathogenesis. However, the certain differences such as the lack of vaccine for ASF and the possibility that this disease can be transmitted by vectors are accounted for in the ASF strategy.

Information on Outbreak Management.

Summary of initial action on suspect cases

Level ASF
0 All restrictions on premises lifted no further action.
1 Suspect animals left alive and observed. Samples submitted for laboratory diagnosis. Premises restrictions imposed.
2 Sick pigs may be killed while the rest are kept left alive and observed. Samples submitted for laboratory diagnosis.
Premises restrictions imposed.
Option to impose temporary control zone
3 All animals on the premises are pre-emptively slaughtered. Samples submitted for laboratory diagnosis. Premises restrictions imposed.
4 Would not apply

Premises Controls

Upon suspicion of disease a temporary control zone restricting the movement of animals within a certain area may be also be established. The location and extent of the zone would depend on all the relevant information available at the time. The zone would be declared as a precautionary measure until the full nature of the outbreak became apparent.

The following policies will be applied on confirmation of ASF.
(Note: The first case will be confirmed by the CVO following a laboratory diagnosis).

  • On suspicion of ASF, a temporary control zone can be established, restricting the movement of animals within a certain area. The location and extent of the zone would depend on all the relevant information available at the time. The zone would be declared as a precautionary measure until the full nature of the outbreak became apparent.
  • A PZ will be imposed with a radius of 3 km around the Infected Premises. Regular veterinary patrol visits of all premises with pigs within this area will take place. All pigs will be required to be kept in their living quarters or other place where they can be isolated. Movements of animals would be restricted within the area.
  • A SZ with a minimum radius of 10km from the Infected Premises would also be established. Movement restrictions would also apply here.
  • Footpaths will be closed only on Infected Premises and Suspect Premises.
  • Diseased and other pigs on the Infected Premises will be killed as soon as possible.
  • Dangerous contacts will be identified. Where the risk of exposure to virus is high, the pigs will be slaughtered and laboratory samples taken to check for disease. Where the risk of exposure is assessed as not high, restrictions on the premises will be in place for 21 days and regular veterinary visits undertaken.
  • Disposal of carcases by incineration would be implemented immediately with rendering as the next option and other disposal routes being available as an additional resource subject to environmental, land use planning and public health considerations.
  • Surveillance for vectors will be undertaken on the IP as part of the epidemiological enquiry.
  • Export health certificates for pigs and pig by- products will be withdrawn. Exports from GB of susceptible animals during the risk period will be identified and notified to the importing countries.
  • Once the cleansing and disinfection of an infected premises has been completed satisfactorily, the premises will remain under restrictions for at least 30 days.

Vaccination

There is currently no vaccine available for the control of African Swine Fever.

Compensation

The African Swine Fever (Compensation) Order 1980 says that where an animal was infected with African swine fever the compensation shall be half the value of the animal immediately before it became infected, and in every other case the compensation shall be the value of the animal immediately before it was slaughtered.

Contingency planning

Defra's revised Contingency Plan for Exotic Animal Diseases was laid before Parliament on 10th December 2007. The plan covers arrangements for dealing with a range of exotic animal diseases, including Foot and Mouth Disease, Avian Influenza and, for the first time, Rabies and Bluetongue. Further information...

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Page last modified: August 28, 2008
Page last reviewed: 30 January 2007

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