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Disease factsheet: Avian influenza

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

Avian Influenza (Bird flu) homepage - Current information about highly pathogenic avian influenza.

Description

Avian influenza is a highly contagious viral disease affecting the respiratory, digestive and/or nervous system of many species of birds. It is caused by a Type A influenza virus. It is a notifiable disease and suspect cases must be notified to the local State Veterinary Service Divisional Veterinary Manager. There are two types of avian influenza virus, low pathogenic (LPAI) and highly pathogenic (HPAI). Within the LPAI types there is evidence that certain H5 and H7 viruses may mutate and become highly pathogenic.

History and spread of the disease

Avian influenza was known as "fowl plague". It first appeared in Italy more than 100 years ago (around 1878). Avian influenza was first recognized in the United States in 1924-25. It occurred again in 1929. It was eradicated both times. Outbreaks due to HPAI were recorded in the Pennsylvania area, USA, in the years 1983-84.

A serious outbreak of HPAI in the Netherlands in 2003, spreading to Belgium and Germany, affected some 250 farms and necessitated the slaughter of more than 28 million poultry.

The H5N1 strain of avian influenza, which surfaced in South East Asia in early 2004, has led to the destruction of millions of birds, and started to spread west through Europe and Africa.

There were also a small number of cases of avian influenza in the USA and Canada early in 2004. The USA strain in Texas was, however, identified as H5N2, not the same as the strain in South-East Asia and the strain in Canada was H7.

A series of wild bird outbreaks have occurred across Europe. The only transfers to domestic poultry have occurred in France, Sweden, Denmark, Germany and Hungary but with early detection and effective control these were eradicated quickly.

Most recent GB outbreaks

The latest information on the current situation is available. Archive of avian influenza incidence in the UK is available.

The disease

Clinical signs

Typically HPAI presents suddenly with affected birds showing oedema (swelling) of the head, cyanosis (blue discolouration) of the comb and wattles (neck and throat area), dullness, a loss of appetite, respiratory distress, diarrhoea and a drop in egg production. Birds can be infected with LPAI without showing any signs of disease. However, there can be considerable variation in the clinical picture and severity of the disease associated with the type of birds infected and whether birds are also suffering from other diseases. Photos of clinical signs.

Transmission
  • Wild birds may be implicated in the introduction of the disease to domestic poultry
  • Direct contact with secretions from infected birds, especially faeces
  • Contaminated vehicles, equipment, personnel, clothing, water or feed.

Legislation for control of avian influenza

NB: this note describes the legislation and controls in England. Similar provisions apply in Scotland, Wales and Northern Ireland.

The Animal Health Act 1981 as amended in 2002 provides most of the domestic powers for the control of outbreaks of avian influenza. The Avian Influenza and Newcastle Disease (England and Wales) Order 2003 made under the amended Act extends new powers to these two diseases. The powers include slaughter of diseased poultry, poultry suspected of disease and poultry exposed to disease and the ability to slaughter preventively - ‘the firebreak cull’.

EC Directive and domestic legislation

A revised Directive (2005/94/EC) Adobe acrobat pdf file (218 KB) for the control of avian influenza (H5 and H7) in poultry and other captive birds in the Community was adopted on 20 December 2005. The Directive maintains the basic strict requirements for notification of disease, slaughter of infected birds and movement controls but allows for the first time a flexible risk-based approach in response to individual situations. It also adds other new provisions such as surveillance in poultry for the low pathogenic strain of the avian influenza virus and allows for controls if this strain is found. It also introduces powers to allow mammals, particularly pigs on infected premises, to be tested for avian influenza virus, for controls to be put on them, and for their slaughter if necessary.

The Avian Influenza and Influenza of Avian Origin in Mammals (England) (No. 2) Order 2006 Adobe acrobat pdf file (622 KB) (referred to as the AI Order) made under the Animal Health Act 1981, implements the majority of the requirements of the new Directive and also takes account of issues arising from the consultation exercise and from the outbreak of LPAI in Norfolk. It replaces the Avian Influenza and Influenza of Avian Origin in Mammals (England) Order 2006 which was made as an emergency measure on 27 April 2006 to allow for the control of the outbreak in Norfolk. The Diseases of Poultry (England) Order 2003 has been revoked as far as it relates to avian influenza.

The Avian Influenza (Vaccination) (England) Regulations 2006 Adobe acrobat pdf file (179 KB) made under the European Communities Act 1972 implement the vaccination requirements of the new Directive. Vaccination of birds against avian influenza is prohibited unless with Defra’s consent. The Directive allows for emergency or preventive vaccination in certain circumstances and if a plan has been approved by the Commission (although emergency vaccination can take place in advance of this approval as long as certain movement controls, as laid down in the Directive, are put in place).

Further information on vaccination policy.

EC Decisions and domestic legislation

The Commission has introduced various Decisions to supplement the provisions of the Directive in response to the virulent strain of the disease, H5N1. These Decisions have been implemented in our domestic legislation. The Commission have also reviewed these Decisions and it is possible that there will be further changes.

Decision 2005/734 as amended Adobe acrobat pdf file (Link to the EU website) - The power to impose preventive measures subject to a risk assessment (including housing of birds and a ban on bird gatherings subject to a licensing regime) are now included in the AI Order.

Decision 2006/415 Adobe acrobat pdf file (Link to the EU website) - This Decision provides for controls to supplement the Directive should the avian influenza virus of the strain H5N1 be found in poultry. It provides for additional restrictions in control zones (in the Decision called Area A and Area B) around a suspect or infected premises. The controls apply to poultry and day old chicks, other captive birds, hatching eggs, wild game products and poultry by products.

The Avian Influenza (H5N1 in Poultry) (England) Order 2006 Adobe acrobat pdf file (80 KB) implements this Decision in domestic legislation. Further information on controls if H5N1 is found in poultry.

Decision 2006/474 Adobe acrobat pdf file (Link to the EU website) allows member states to vaccinate birds kept in zoos and approves the UK’s zoo bird vaccination plan. This has been transposed by the Avian Influenza (Preventive Measures) Regulations 2006 Adobe acrobat pdf file (131 KB) (Explanatory Memorandum PDF logo (31 KB)). A decision on whether to allow such vaccination of zoo birds to go ahead will be based on a risk assessment.

Decision 2006/563 (Link to the EU website) - This Decision provides for controls if the H5N1 strain of avian influenza is found in wild birds. Avian Influenza (H5N1 in Wild Birds) (England) Order 2006 Adobe acrobat pdf file (110 KB) implements this Decision in domestic legislation. Further information on controls if H5N1 is found in wild birds.

Main aspects of control of avian influenza in poultry and other captive birds

If avian influenza is suspected or confirmed in poultry or other captive birds in Great Britain, various disease control measures would come into effect on the premises and surrounding area in accordance with the Avian Influenza and Influenza of Avian Origin in Mammals (England) (No. 2) Order 2006 Adobe acrobat pdf file (622 KB)

If HPAI of the type H5N1 was suspected or confirmed in poultry, the additional requirements of the Avian Influenza (H5N1 in Poultry) (England) Order 2006 Adobe acrobat pdf file (80 KB) would also apply.

The measures that would be required in an outbreak of avian influenza in poultry and other captive birds would vary depending on the type of disease and can be grouped as:

  • Measures on suspicion of avian influenza
  • Additional measures on suspicion of HPAI H5N1 in poultry
  • Measures on confirmation of HPAI
  • Additional measures on confirmation of HPAI H5N1
  • Measures on confirmation of LPAI
Measures on suspicion of avian influenza

On notification of suspected avian influenza, there is an obligation on the owner or keeper of the birds not to move anything off the premises that could spread disease pending the arrival of the State Veterinary Service Veterinary Inspector to carry out an investigation.

The Veterinary Inspector serves a notice on arrival at the premises placing controls on the movement of poultry, other captive birds, people, animals, eggs, vehicles and other things liable to spread disease to and from the premises. Poultry and captive birds on site must be housed or otherwise isolated from wild birds. Disinfection facilities must be installed at entrances and exits of the premises and bird housing. Schedule 1 of the AI Order Adobe acrobat pdf file (622 KB) describes the measures in detail.

It is possible to disapply some of the measures in Schedule 1 based on a risk assessment or increase controls by applying some or all of the measures in Schedule 2 of the AI Order Adobe acrobat pdf file (622 KB) (which includes slaughter of poultry and other captive birds, tracing of anything liable to transmit disease, cleansing and disinfection of premises and action to reduce the risk of spread to wild birds).

Depending on the level of suspicion and risk, temporary control (TCZ) and temporary movements restriction zones (TMRZ) may be declared around the suspect premises. The TMRZ may be regional or national. The size of the zones and the measures in them would be based on a risk assessment.

Restrictions on a suspect premises and any zones declared will be revoked if disease is not confirmed.

Additional measures on suspicion of HPAI H5N1 in poultry

If H5N1 is suspected in poultry, zones must be declared round the suspect premises. The inner zone (Area A) would be a minimum of 10km around the suspect premises. An outer zone (Area B) would also be declared and the size based on a risk assessment. The measures in the zones would also be based on a risk assessment.

Measures on confirmation of HPAI

Infected premises

If HPAI is confirmed on a premises, a notice is served on it continuing to apply the measures in Schedule 1 of the AI Order Adobe acrobat pdf file (622 KB) but also applying Schedule 2 Adobe acrobat pdf file (622 KB) if this has not already been done on suspicion.

The default position is that all infected poultry and captive birds would be slaughtered. In a special category premises this rule may be disapplied as long as disease control is not threatened. A special category premises is defined as a non-commercial holding, a circus, a zoo, a pet bird shop, a wild life park and a fenced area where poultry or other captive birds are kept for scientific purposes or for purposes related to the conservation of endangered species and for officially recognised rare breeds. Any such derogations will be decided on a case by case basis.

Eggs on the infected premises would also be destroyed.

The occupier must arrange for the premises to be cleansed and disinfected in accordance with the instructions of a Veterinary Inspector.

Veterinary Inspectors would carry out an investigation at infected premises to identify where eggs and poultry had gone so that they could be traced and destroyed or placed under restrictions as required under the AI Order. Contact premises would also be identified and placed under restriction. Poultry and captive birds at high risk ‘dangerous contact’ premises would be slaughtered.

An infected premises may not be re-stocked until at least 21 days after final cleansing and disinfection of the premises.

Information on Avian Influenza disease control (slaughter) policy.

Controlled zones

In most cases where HPAI is confirmed a protection and surveillance zone will be declared. A restricted zone may also be declared. However, if HPAI is confirmed in a hatchery or in other captive birds in special category premises the legislation allows for a greater degree of flexibility in applying protection and surveillance zones and the measures in them as long as the risk of disease spread is contained.

Protection Zone (PZ)

The PZ must have a radius of at least 3km around the outbreak point. The measures applying on premises where there are poultry or other captive birds within the PZ are set out in Schedule 4 of the AI Order Adobe acrobat pdf file (622 KB). These include:

  • Housing or isolation of poultry and other captive birds;
  • Movement restrictions on poultry, other captive birds, mammals, eggs, poultry meat, carcases and poultry waste except where licensed;
  • Biosecurity measures for people, premises and vehicles;
  • A ban on bird gatherings;
  • A ban on the release of game birds.

Footpaths may be closed in a PZ if a veterinary risk assessment shows this is necessary to reduce the risk of disease spread. However, Government policy is to keep the countryside open for business as far as possible during a disease outbreak and this measure is likely to be applied only to footpaths going through or around infected premises.

The PZ must be in place for at least 21 days after the preliminary cleansing and disinfection of the infected premises and then becomes part of the surveillance zone.

Surveillance Zone (SZ)

The SZ must have a radius of at least 10km around the outbreak point. The measures applying on premises where there are poultry or other captive birds within the SZ are set out in Schedule 5 of the AI Order Adobe acrobat pdf file (622 KB). The measures in the zone are similar to those in the PZ but slightly less restrictive. For example, there are no restrictions on the movement of poultry meat and carcases.

The SZ must be in place for at least 30 days after the preliminary cleansing and disinfection of the infected premises. The duration of the PZ and SZ will take account of surveillance in the area showing that there is no disease present.

Restricted Zone (RZ)

An RZ may also be declared covering the whole or part of Great Britain. Movements of poultry and eggs would be subject to licence.

The RZ is likely to reduce in size as the extent of disease spread becomes clear. The duration of the RZ will be based on a risk assessment.

Further information on the controls applying to movement of poultry and eggs in an HPAI controlled zone Adobe acrobat pdf file (208 KB)

Additional measures on confirmation of HPAI H5N1 in poultry

When H5N1 is confirmed in poultry, The Avian Influenza (H5N1 in Poultry) (England) Order 2006 Adobe acrobat pdf file (80 KB) requires additional measures in the controlled zone. The measures in the AI Order continue to apply.

Area A

Area A is likely to be the same as the PZ and SZ declared under the AI Order and of the same duration. The additional controls that will apply include restrictions on the following movements:

  • products from wild feathered game, unless the game originating from Areas A or B has been subjected to official controls (and has an identification mark), or is heat treated. All such moves must be licensed. If the game originates from outside the Areas, the products must meet certain hygiene requirements;
  • avian products, unless meeting certain conditions (for example moving for specific disposal or treatment processes);
  • treated and untreated poultry and game bird feathers. Treated feathers may move subject to certain conditions.

Area B

Area B is likely to be the same as all or part of the RZ declared under the AI Order. The duration will be based on risk. The additional controls that will apply include a ban on bird gatherings and restrictions on the following movements from Area B to the area not restricted by an H5N1 controlled zone:

  • live poultry, unless moving (under licence) to a designated slaughterhouse or to other premises if they remain there for 21 days, or to other countries with their agreement;
  • day old chicks, unless under licence;
  • hatching eggs, unless they are moving under licence from farms subject to a veterinary inspection or are moving to a designated hatchery. Movements to other countries must be with their agreement. Eggs may also move to designated premises for scientific purposes.
  • products from wild feathered game, unless the game originating from Areas A or B has been subjected to official controls (and has an identification mark), or is heat treated. All such moves must be licensed. If the game originates from outside the Areas, the products must meet certain hygiene requirements;
  • avian by products unless meeting certain conditions (for example moving for specific disposal or treatment processes).
  • treated and untreated poultry and game bird feathers unless meeting certain conditions.

Further guidance on movements.

Measures on confirmation of LPAI

Infected premises

If LPAI is confirmed on a premises, a notice is served on it applying measures similar to those for a confirmed case of HPAI. These can be found in Schedule 6 of the AI Order Adobe acrobat pdf file (622 KB).

The default position is that all infected poultry and captive birds would be slaughtered. In a special category premises this rule may be disapplied as long as disease control is not threatened. Any such derogations will be decided on a case by case basis.

Eggs on the infected premises would also be destroyed. However, this rule may, subject to risk, be disapplied to hatching eggs at special category premises.

The occupier must arrange for the premises to be cleansed and disinfected in accordance with the instructions of a Veterinary Inspector.

Veterinary Inspectors would carry out an investigation at infected premises to identify contact premises.

An infected premises may not be re-stocked until at least 21 days after final cleansing and disinfection of the premises .

Controlled zone

If LPAI is confirmed a low pathogenic avian influenza restricted zone will be declared. However, if LPAI is confirmed in a hatchery or in other captive birds in special category premises the legislation allows for a greater degree of flexibility in applying the zone and the measures in them as long as the risk of disease spread is contained.

Low pathogenic avian influenza restricted zone (LPAI RZ)

The LPAIRZ must have a radius of at least 1km around the outbreak point.

The measures applying on premises where there are poultry or other captive birds within the LPAIRZ are set out in Schedule 7 of the AI Order Adobe acrobat pdf file (622 KB). These include:

  • Movement restrictions on poultry, other captive birds, mammals, eggs carcases and poultry waste except where licensed;
  • Biosecurity measures for people, premises and vehicles;
  • A ban on bird gatherings;
  • A ban on the release of game birds.


Further information on the controls applying to movement of poultry and eggs in an LPAIRZ Adobe acrobat pdf file (107 KB)

The LPAI RZ must be in place for at least 21 days after the preliminary cleansing and disinfection of the infected premises. The duration will take account of surveillance in the area showing that there is no disease present.

Main aspects of control of avian influenza H5N1 in wild birds

If avian influenza of the subtype H5N1 is confirmed in a wild bird the Avian Influenza (H5N1 in Wild Birds) (England) Order 2006 Adobe acrobat pdf file (110 KB) applies. The legislation is designed to increase monitoring and surveillance to help prevent the spread of the disease to poultry by detecting such spread at an early stage.

Controlled area

The legislation provides for controlled areas around the wild bird location. The information below describes the default position. However, the legislation allows for the size and shape of the controlled areas, the measures in them and the duration for which these are applied to be based on the risk of disease spreading to poultry or other captive birds. This means that there is scope for each case to be assessed throughout its duration and treated accordingly.

Control Area

The Control Area would usually have a radius of at least 3km around the wild bird location. The measures applying in the Control Area include:

  • Veterinary inspection of all commercial poultry premises. Targeted risk based visits to non commercial poultry and other captive bird holdings;
  • Increased biosecurity, wild bird surveillance and publicity campaigns;
  • Movements of poultry, other captive birds and hatching eggs restricted except under licence.
  • Movements of meat and meat products from poultry and wild feathered game, by products from poultry, wild feathered game and other captive birds, and unprocessed manure restricted unless meeting certain conditions.
  • Biosecurity measures for premises, people and vehicles;
  • A ban on the hunting of wild birds, the release of game birds and bird gatherings.

The Control Area must be in place for at least 21 days following the date of collection of the samples from the infected wild bird. The duration will take account of surveillance in the area showing that there is no disease present.

Monitoring area

The Monitoring Area would usually have a radius of at least 10 km around the wild bird location. The measures applying in the Monitoring Area include:

  • Movements of poultry, other captive birds and hatching eggs restricted except under licence.
  • Biosecurity measures for premises, people and vehicles;
  • A ban on the hunting of wild birds, the release of game birds and bird gatherings.

The Monitoring Area must be in place for at least 30 days following the date of collection of the samples from the infected wild bird. The duration will take account of surveillance in the area showing that there is no disease present.

Further information on the controls applying to movement of poultry and eggs in a wild birds controlled zone Adobe acrobat pdf file (158 KB)

Further information on Outbreak Management.

Avian influenza in pigs

If Avian Influenza is confirmed in wild birds near to a pig unit, a risk assessment will be carried out, to provide the basis for advice and instruction given by the SVS to keepers of outdoor pigs in the area. It is not proposed that there will be a requirement to house pigs.

If HPAI were identified in pigs during ongoing surveillance the unit would be placed under movement restrictions.

Compensation

Schedule 3 of the Animal Health Act 1981 states that compensation for poultry which are slaughtered for disease control purposes but which are not diseased shall be paid at the value immediately before slaughter.

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...

Further information

Page last modified: June 6, 2008

Department for Environment, Food and Rural Affairs