Avian influenza in backyard poultry

Over the last few weeks, there have been several cases of Avian Influenza in the UK in both wild birds and poultry. Many (though not all) of the cases involved the strain HPAI H5N8. As such, the risk of bird flu occurring in the UK has been raised to "very high" in wild birds and "medium/high" in poultry, depending on the standard of biosecurity. 

On Monday 14th December 2020, a housing order came into force requiring all poultry and other captive birds in the UK to be kept indoors. This came following an announcement of an Avian Influenza Prevention Zone (AIPZ) across the whole of GB on 11th of November 2020, requiring all poultry keepers to increase their levels of biosecurity. 

To help poultry owners to comply with biosecurity guidance, the BSAVA and British Veterinary Poultry Association (BVPA) have put together a Q&A to give vets an easy reference point to provide advice to backyard poultry keepers. In addition, the BSAVA has compiled a special collection of resources on backyard poultry in the BSAVA library, which is freely available until the end of January 2021. 

What is avian influenza? 

Avian influenza (AI) is highly contagious viral disease that affects both domestic and wild birds. AI viruses are usually classified into two categories: low pathogenicity avian influenza (LPAI), which typically causes no or very few clinical signs in poultry, and high pathogenicity avian influenza (HPAI) which typically causes high mortality rates in poultry1. Both Public Health England (PHE) and the Food Standards Agency (FSA) have stated that the risk to human health is very low. 

What are the clinical signs of disease in poultry?

The type and severity of clinical signs displayed will be dependent upon the strain of the virus and the species affected; some species such as ducks and geese may show few clinical signs2

The current H5N8 strain is causing high mortality in poultry. Other clinical signs may include: cyanosis and oedema of the face, respiratory signs, nervous signs, diarrhoea, a decrease in egg production and poor quality egg shells. 

How is the disease spread? 

Wild bird species are the natural host and reservoir for all types of avian influenza, naturally carrying the virus in their respiratory and intestinal tracts, commonly without developing signs of the disease1,3. The virus is predominantly spread via body secretions, both directly and indirectly2

Migratory birds (predominantly waterfowl and gulls) can spread the disease over a wide geographical area3. People can then carry the virus from wild bird droppings on their boots into chicken sheds/coops. As such, it is recommended to have boot dips at the entry to all poultry sheds. 

Furthermore, water ingress through leaks in roofs or via water coming up through the floor of the shed has been implicated in many cases. Therefore, good maintenance of coops/sheds is essential. 

Why is the winter a higher risk period for avian influenza? 

The UK is at increased risk of avian influenza from migrating birds during winter2. Furthermore, avian influenza viruses are able to survive for prolonged periods of time in the environment, particularly in low temperatures4.

How can I prevent my birds from contracting avian influenza? 

All keepers of poultry should ensure that they uphold good levels of biosecurity to prevent disease entering their flock. This includes:

maintaining good levels of hygiene including cleaning and disinfecting any equipment (e.g. feeders and drinkers) that comes into contact with poultry, and regularly disinfecting hard surfaces; 

changing or disinfecting shoes before entering/leaving to avoid transferring faeces in/out of the poultry enclosure. It is recommended that a boot dip (containing a DEFRA approved disinfectant) is placed at the entry to all poultry areas. The disinfectant must be at the right concentration and changed regularly in accordance with the manufacturer's instructions;

minimizing contact with wildlife by humanely controlling rodents and deterring wild birds. Contact with wild birds can be minimized by placing food and water in an enclosed area such as the coop, and preventing poultry from accessing ponds/standing water frequented by wild bird populations, for example by erecting temporary fencing. As of 14th December 2020, all poultry need to be housed but there is an option to allow poultry access to grass if the range area is netted above to prevent wild bird access;

where possible, keeping birds of different poultry species separate (e.g. ducks and geese should be separate from chickens). This is a mandatory requirement of the AIPZ as of 14th December 2020;

contact your vet if any of your birds show signs of disease, or die suddenly and unexpectedly.

What should I do if I suspect avian influenza? 

Avian influenza is a notifiable disease. If it is suspected, it must be reported immediately:

In England, contact the Defra Rural Services Helpline on 03000 200 301

In Wales, contact your local Animal and Plant Health Agency (APHA) office on 0300 303 8268

In Scotland, contact your local Field Services Office

For keepers in Northern Ireland, contact your local DVO. 

Further information 

The BSAVA Manual of Backyard Poultry Medicine and Surgery is a comprehensive starting point for veterinary practitioners wanting information about backyard poultry medicine and surgery, including infectious diseases such as AI. 

In Great Britain, any poultry keepers with more than 50 birds are legally required to register their flock with the Great Britain Poultry Register. It is, however, recommended that keepers of any number of birds register with Defra so that they can be contacted in the event of a disease outbreak (including avian influenza). For more information on how to register a flock, please visit the following website

For the most up-to-date information in your area, please visit the following websites: 


1. World Organisation for Animal Health (OIE) (2019) Avian Influenza Portal

2. Animal and Plant Health Agency (APHA) (2019) Guidance: Avian influenza (bird flu)

3. Stallknecht, D. E., Brown, J. D. (2007) Wild birds and the epidemiology of avian influenza. Journal of Wildlife Diseases. 43(3), pp. S15-S20.

4. Iowa State University (2015) Avian Influenza

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