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ARCHIVE: Swine Vesicular Disease

Swine Vesicular Disease is a different disease to Swine Influenza. See the Swine Influenza pages for more information.

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

Animals affected

Pigs.

History and spread of the disease

Swine vesicular disease (SVD) is contagious disease caused by a virus. It was first diagnosed and probably first appeared in Italy in 1966. There was much speculation as to the origin of this apparently new disease, and some laboratory data supported the idea that it was a new virus derived in part from a human enterovirus. The first outbreak of SVD in Great Britain was in 1972. Over the next ten years 532 cases involving a total of 322,081 pigs were confirmed before the disease was eradicated from this county in 1982.

SVD has persisted in Italy, where it is now considered endemic. The rest of Europe is free from the disease apart from one case in Portugal reported in June 2007.

Clinical signs

The clinical signs are indistinguishable from foot-and-mouth disease in pigs. The incubation period of SVD is between two and seven days, and following a transient fever of up to 41 degrees Centigrade, vesicles (blisters) develop on the coronary band, typically at the junction with the heel. The disease usually appears suddenly but does not spread with the same rapidity as foot-and-mouth disease. Mortality is low but in acute cases there can be some loss of production. In the initial stages there is fever and a transient loss of appetite. Lameness develops due to the eruption of vesicles at the top of the hooves and between the toes. Vesicles may also develop on the snout, tongue and lips. The surface under the vesicles is red and this gradually changes colour as healing develops. When severe vesication has occurred at the hoof head, the entire hoof may be shed. In less severe cases the healed lesion may grow down the hoof and its presence is indicated by a black transverse mark. Recovery is usually complete within two to three weeks. This description of the signs of SVD will vary according to the age of the pigs affected, the conditions under which they are kept, and the strain of SVD virus involved. Disease caused by mild strains can go unnoticed, particularly in pigs kept on grass or housed in deep straw. Younger animals are more severely affected, although mortality due to SVD is rare. Nervous signs are unusual. Photos of clinical signs.

Diagnosis

Clinically, SVD cannot be distinguished from FMD. Following notification of a suspected outbreak, samples are sent to the Institute for Animal Health at Pirbright. As much vesicular fluid and infected epithehal tissue as possible must be collected in 50-50 PBS glycerol buffered to pH7.2, for although SVD virus is pH stable, FMD virus is not, and must be protected during transport. It may be necessary to slaughter or sedate an affected pig to collect adequate samples. In addition, because the disease may have been present unnoticed on the premises for some time, serum samples from in- contact and other groups of pigs on the farm should be submitted for evidence of antibodies to the SVD virus.

At Pirbright, tissue samples will be tested by ELISA for virus antigen and put onto susceptible tissue culture for virus recovery. A positive result may be submitted within four hours. If initially negative, the tissue will be cultured for 96 hours before a final result is given. Serum is also tested by ELISA and virus neutralisation.

Legislation

The Swine Vesicular Disease Order 1972 (as amended), extends the definition of disease in Section 84 of the Diseases of Animals Act 1950 (now replaced by Section 88 of the Animal Health Act 1981) to include Swine Vesicular Disease for all the purposes of the Act, and enables pigs affected or suspected of being affected with that disease, or exposed to infection, to be slaughtered. It also applies certain provisions relating to Foot and Mouth Disease for the purpose of Swine Vesicular Disease. 

The Swine Vesicular Disease (Compensation) Order 1972, provides for compensation to be paid for animals slaughtered under Section 17 of the Diseases of Animals Act 1950 (now Section 32 of the Animal Health Act 1981) because they were affected or suspected of being affected with Swine Vesicular Disease or had been exposed to infection.

This Order provides that, where an animal is affected with SVD, the level of compensation shall be the value of the animal immediately before it became infected. In every other case, compensation shall be the value immediately before it was slaughtered.

The Pigs (Records, Identification and Movement) Order 2003 also provides for the tracing and movement control of pigs.

EU Legislation

Council Directive 92/119 EEC introducing general Community measures for the control of certain animal diseases and specific measures relating to that in the event of a confirmed case of SVD a protection zone of 3km radius from the infected holding, and a surveillance zone of at least 10km radius will be set up. All animals of susceptible species on the infected holding must be killed on site. Directive 92/119 also prescribes the procedure for cleansing and disinfection in cases of SVD, and stipulates minimum time limits before restocking can take place.

It is intended to replace the 1972 Order, to update in line with current procedures and fully implement the provisions of the Directives referred to above.

Enforcement Provisions: Local Authorities will execute and enforce the provisions of the Swine Vesicular Disease Order 1972, other than where the legislation makes specific provisions otherwise.. The penalties for not complying with the legislation are detailed in Part V of the Animal Health Act 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 SVD
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.
Option to impose temporary control zone.
4 Would not apply

NB: The first clinical case would be treated as though FMD were suspected, until such time as the results were available.

Disease Control Strategy

The disease control strategy adopted will be consistent with the UK’s EU obligations and in line with the appropriate EU legislation. The Government’s objective in tackling any fresh outbreaks of SVD will be to eradicate the disease as quickly as possible and to maintain the UK’s disease-free status. In doing so, the Government will seek to select a control strategy which:

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

Information on Outbreak Management.

Control Policies

On suspicion of disease the Secretary of State will make a declaration establishing a Temporary Control Zone around the suspect premises. This will be of a size considered necessary to prevent the spread of disease. Within the Temporary Control Zone movements of animals to and from premises (including into or out of the zone) are not allowed. A Supplementary Movement Control zone may also be established, restricting the movement of animals in a wider area.

The following policies will be applied on confirmation of SVD:

(Note: The first case will be confirmed by the CVO following Laboratory diagnosis)

  • Export health certificates for animals and animal products will be withdrawn. Exports from GB of susceptible animals during the risk period will be identified and notified to the importing countries;
  • Diseased and other susceptible animals on infected premises will be killed with a target of within 24 hours of report. Those identified as dangerous contacts will be culled with a target of within 48 hours of report;
  • A Protection Zone will be imposed with a minimum radius of 3km around the Infected Premises and a Surveillance Zone with a minimum radius of 10km. In the Protection Zone no animal movements will be allowed except for movement to emergency slaughter. In both the Protection and Surveillance Zones, there will be requirements for increased levels of biosecurity on farms, cleansing and disinfection (C&D) of vehicles, people and machinery moving on/off farms. Movement of animals, animal products, feed and bedding will be prohibited, except under licence. Products from animals in these zones will be subject to treatment to ensure destruction of the SVD virus. This is an animal health measure rather than a public health measure;
  • Disposal by incineration will 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.

Further details of Outbreak Management.

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...

Related Pages

Page last modified: September 9, 2009