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Disease factsheet: Classical swine fever

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

29 May 2008 - International Disease Monitoring - Preliminary Outbreak Assessment: Classical swine fever – Bulgaria.

Definition

Classical swine fever (CSF) is a highly contagious viral disease of pigs. In its acute form the disease generally results in high morbidity and mortality.

History and spread of the disease in Great Britain

CSF was first confirmed in this country in 1864 and was initially allowed to spread unchecked until 1878, when legislation for its control was introduced. The disease persisted for many years until it was finally eradicated from Great Britain in 1966 (see below for details of outbreaks). Since then there have been sporadic outbreaks in 1971 and 1986.

A more serious outbreak in East Anglia in 2000 affected 16 farms. A total of 74,793 pigs including those on contact farms were slaughtered to eradicate the disease. The cause of this most recent outbreak was not finally established but was most likely the result of pigs eating a contaminated imported pork product.

Clinical signs

The symptoms of CSF and African swine fever (ASF) are almost identical and either may occur in chronic or acute form. Laboratory diagnosis is necessary to distinguish CSF from ASF. The incubation period for CSF is variable but is usually between five and ten days. In the acute form pigs develop a high temperature (40.5 degrees C or 105 degrees F), then become dull and go off their food. Other symptoms seen can vary but will include some or all of the following:

  • Constipation followed by diarrhoea
  • Gummed-up eyes
  • Coughing
  • Blotchy discolouration of the skin
  • Abortion, still births and weak litters
  • Weakness of hindquarters.
  • Nervous signs including convulsions and tremors in new born piglets.

Photos of clinical signs

Differential diagnosis

  • African swine fever
  • Infection with bovine viral diarrhoea virus
  • Salmonellosis
  • Erysipelas
  • Acute pasteurellosis
  • Other viral encephalomyelitis
  • Streptococcosis
  • Leptospirosis
  • Coumarin poisoning
  • Porcine Dermatitis and Neopathy Syndrome (PDNS)

How is this disease spread?

The main source of CSF appears to be from pigs eating infected pork or pork products. In this form the CSF virus can remain active for many months.

The movement of infected pigs is a common method of spreading CSF. Apparently healthy pigs may be incubating disease and recovered pigs can excrete the virus for long periods of time.

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

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

Great Britain operates strict controls over the import of meat and meat products primarily to guard against the introduction of animal diseases. While these methods are generally effective, it is possible that on occasions meat and meat products infected with an animal disease virus such as swine fever may accidentally enter the country.

If, despite these precautions, swine fever viruses entered the country the risk of them 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 pig 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.

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 CSF 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

The Animal Health Act 1981 provides powers for the control of CSF. It includes the following measures for disease control:

  • Slaughter of diseased pigs, pigs suspected of disease and those exposed to disease.
  • The use of vaccination as a preventative measure for disease control. This allows Ministers to authorise the use of CSF vaccine in any pig which has been in contact with a diseased animal or has been exposed to the disease, or which is in an area declared to be an “infected area” (see below).
    N.B: At present there is no CSF vaccine with a marketing authorisation for use in England.

The Act also provides for compensation to be paid for animals slaughtered and prescribes how the level of compensation is arrived at.

The Classical Swine Fever (England) Order 2003, made under the Animal Health Act 1981, implements Council Directive 2001/89/EC for the control of classical swine fever. In Scotland, the Classical Swine Fever (Scotland) Order 2003 applies, and in Wales the Classical Swine Fever (Wales) Order 2003 applies. The provisions of these Orders include the following measures:

  • Requirement for notification of suspicion of CSF.
  • 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 zone 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).

European Union Legislation: Council Directive 2001/89/EC 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 CSF 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 protection zone (PZ)(minimum 3km) and a surveillance zone (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.
  • In very specific circumstances a plan for emergency vaccination can be agreed with the Commission.
  • Surveillance of any feral pigs.

Enforcement Provisions: Local Authorities will execute and enforce the provisions of the Classical Swine Fever (England) Order 2003, other than where the legislation makes specific provisions otherwise. Similar policies exist for legislation in Scotland and Wales. The penalties for not complying with the legislation are detailed in Part V of the Animal Health Act of 1981.

The table below indicates the local veterinary action to be taken in relation to the level of suspicion.

Summary of initial action on suspect cases

Level CSF
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

Disease Control Strategy

The disease control strategy will be consistent with the UK’s EU obligations and inline with the appropriate EU legislation. The Government’s objective in tackling CSF 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

Information on Outbreak Management.

Premises Controls

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

  • 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.
  • 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.
  • Footpaths will be closed only on Infected Premises and Suspect Premises.
  • It is unlikely that emergency vaccination would be used as a measure of disease control for CSF, due to the absence of challenge tested vaccine. However if vaccination were to be used in certain limited circumstances its is most likely that a policy of suppressive vaccination would be implemented.
  • An Infected Area will be declared with a minimum radius of 10km around an IP and will remain in place for at least 30 days after preliminary C & D of all infected places. An Infected Area consists of a protection zone with a minimum radius of 3 kilometres contained within a surveillance zone with a minimum radius of 10 kilometres.
  • 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.
  • 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

Vaccination would not normally be considered as a control measure in the current CSF control strategy. CSF vaccination is restricted by legislation which states that no person shall administer a CSF vaccine to any pig unless authorised to do so by the Secretary of State.

It is possible that vaccination might be used in areas of very high pig density to prevent the occurrence of unrecognised infection in such areas during a prolonged epidemic.

There are currently no operational arrangements in place to mount a widescale CSF emergency vaccination programme in the event of an outbreak in Great Britain.

Compensation

Schedule 3 to the Animal Health Act 1981 says that where an animal was infected with 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: May 29, 2008

Department for Environment, Food and Rural Affairs