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Avian influenza (bird flu): Control measures for pigs (including pet pigs) in the event of an avian influenza outbreak

The following question and answer brief provides Defra’s current plans for dealing with a number of scenarios in relation to avian influenza in pigs. This is to be the default position. Factors may arise during an outbreak that require us to adopt a different policy. Industry representative bodies will be fully consulted in the event of an outbreak involving pigs.

Is influenza of avian origin in pigs notifiable?

Any person who examines or inspects any mammal or mammal carcase, or who analyses samples from any mammal or mammal carcase, must notify the Divisional Veterinary Manager if he suspects influenza of avian origin, or suspects antibodies to influenza virus of avian origin.

What action will be taken if pigs are located on premises where avian influenza is confirmed in poultry?

Pigs located on a premises where avian influenza is confirmed in poultry (an Infected Premises, or IP) must be tested for avian influenza on the day the infected poultry are culled (or earlier if possible), and again 21 days after that date using EU Directive and Diagnostic manual requirements.

The testing method would be nasal swabs and blood sampling (or tracheal swabs if absolutely necessary). Epidemiological groups of pigs should be sampled to give a 95% confidence of detecting 5% prevalence of infected pigs.

What movement restrictions would apply to pigs on an IP?

Pig movements would already be restricted (as a result of the restrictions on the IP) and will remain in place unless a veterinary inspector confirms the animals are not infected (preferably after a 2nd negative lab result), and licenses the movement from the IP.

What happens if pigs are present in a contact premises to an infected premises?

Pigs on a contact poultry premises (a premises with a link to a poultry premises where disease has been confirmed) would only normally be tested when disease has been confirmed in poultry on that contact premises, or the decision has been taken to slaughter the poultry pre-emptively because the risk of them being infected was high.

What will happen if pigs on premises near to a poultry IP are showing flu-like symptoms?

Decisions would be taken on a case by case basis according to the veterinary risk assessment. If necessary, serological samples may be taken.

Would movement restrictions apply to pigs (including pet pigs) that are in contiguous premises or in or near a Protection Zone (PZ) or Surveillance Zone (SZ)?

There would be no automatic requirement for movement restrictions, surveillance, or testing of pigs on any premises other than an infected premises.

Would all pigs on an infected premises be culled if avian influenza virus is confirmed in the pigs?

There are 2 options available:

  1. If all pigs have been tested and the avian influenza virus is confirmed in only 1 pig in a herd, the individual animal would be culled. Testing and surveillance of the remaining herd would be maintained to see if other naive pigs became infected.
  2. If avian influenza virus is found in several pigs, a decision to cull the whole herd would be made on a case by case basis depending on the risk assessment.

Any veterinary risk assessment in the light of a virus positive result must consider the particular strain of virus, and whether it is known to be communicable to other pigs or man.

There must be careful consideration before precautionary measures (such as culling) are taken. Such measures may be taken if there is clear evidence of transmission between pigs, i.e. pigs have become infected (with or without showing clinical signs of disease) and are replicating and excreting sufficient virus to have infected other pigs in the herd.

It is not necessarily the case that we should kill a pig from which virus has been isolated. For example, it would be possible to isolate virus from the nasal passages of a pig without the pig being truly infected (and replicating/excreting virus). It could merely have been harbouring contaminated dust in its nasal passages.

What restrictions will be in place after pigs have been culled on an IP?

Restocking would be controlled by Defra and would be co-ordinated with any poultry operations on site.

There would not be any restrictions on the movements of any pigs which are not killed out after the IP restrictions are lifted.

Movements of pigs on such premises are restricted until such time as they are licensed by a veterinary inspector or are shown not to have become infected with this virus. Any movement must not result in the spread of the disease.

Would pig meat already in the food chain from premises found to have infected animals be affected?

There is no need for official action.

Will wild animals or feral pigs be culled if avian influenza virus is confirmed in such animals?

Unless a wild animal is captured the situation is unlikely to arise. However, a decision would be taken on a case by case basis after a veterinary risk assessment.

What would happen if avian influenza virus is confirmed in pigs not on an already infected premises?

This could occur in the following circumstances:

  • the disease had been reported by an owner/keeper:
  • the field epidemiologists recommend that we test pigs on a farm next to an infected poultry premises;
  • an unexpected isolation of the avian influenza virus from pig samples or detection of its genome is reported from a laboratory.

The disease control options are the same as that on an IP.

Would movement restrictions apply when avian influenza seroconversion only is confirmed in pigs on an infected premises?

Yes. The premises would remain under restrictions and the movement of pigs would be restricted pending further testing 21 days later to determine if any other pigs have become infected and if there is active circulation of the avian influenza virus.

No further action would be required if the pigs remained sero-negative and virus negative at the subsequent tests done 21 days after the poultry were killed. Restrictions would remain until the premises had been fully cleansed and disinfected and the pigs could be licensed off subject to good vehicle biosecurity.

Will movement restrictions still apply to pigs that are not on an infected premises if avian influenza seroconversion (virus test is inconclusive) only or negative test results are confirmed?

No further action would be necessary if the pigs remained sero-negative and virus negative at the subsequent tests done after 21 days. All restrictions would be removed.

How will you ensure disease spread is limited?

Defra has the power to establish an “avian influenza (restrictions on mammals) zone” if deemed necessary to monitor or control the spread of avian influenza virus in mammals (no confirmation of disease is necessary). This would enable the introduction of stricter biosecurity controls within the zone.


Page last modified: November 14, 2007 13:17

Department for Environment, Food and Rural Affairs