Publication - Advice and guidance

Avian influenza (bird flu): how to spot and report the disease

Published: 27 Nov 2018

Advice on what to do if you suspect there is an outbreak of this infectious disease.

27 Nov 2018
Avian influenza (bird flu): how to spot and report the disease

Avian influenza (bird flu) mainly affects birds. It can also affect humans and other mammals.

Latest situation: There are currently no restrictions. The recent restricted zone in Mid Suffolk, England has been revoked by Defra

There are currently no restrictions on bird keepers in Scotland, and bird gatherings are permitted under licence. We will continue to monitor the situation across the UK and the rest of Europe.

While findings in wild birds are not unexpected for the time of year, it is a timely reminder for all bird keepers to maintain good levels of biosecurity and to remain vigilant for any signs of disease in their flock. 

In addition, we have identified some sites that are at a higher risk of avian influenza and owners of poultry in those areas are strongly encouraged to review their biosecurity arrangements now. See section on Higher Risk Areas below for more details.

Clinical signs

Avian influenza viruses can be classified according to their ability to cause severe disease (pathogenicity) as either highly pathogenic or low pathogenic. The viruses are described by their major antigen determinants, H (for haemagglutinin) and N (neuraminidase). The current strain of concern is a highly pathogenic H5N1.

In birds we are mainly concerned with H5 and H7 subtypes. It is known that the LPAI H5 and H7 virus subtypes can mutate into the highly pathogenic form that causes serious illness and deaths in birds, although in water fowl the disease may not be apparent.

Low pathogenic avian influenza

Typically, infection with LPAI is often difficult to detect, with very few if any clinical signs. An infected flock might show signs of respiratory distress, diarrhoea, a loss of appetite or a drop in egg production of more than 5%. If you are suspicious your flock has any form of avian influenza you must contact your local animal health office immediately.

Highly pathogenic avian influenza

Typically this form of the disease presents suddenly, often with very high mortality, with affected birds developing swollen heads, a blue colouration of the comb and wattles, dullness, lack of appetite, respiratory distress, diarrhoea and significant drop in egg production. However, there can be considerable variation in the clinical picture and severity of the disease. If you are suspicious your flock has any form of avian influenza you must contact your local animal health office immediately.

If you suspect signs of any notifiable diseases, you must immediately notify your Scotland: field service local office at the Animal and Plant Health Agency (APHA). Failure to do so is an offence. Sign up to the APHA Alerts Service to keep up to date with the latest news.

How avian influenza is spread

The disease spreads from bird to bird by direct contact or through contaminated body fluids and faeces. It can also be spread by contaminated feed and water or by dirty vehicles, clothing and footwear.

The avian influenza virus changes frequently, creating new strains, and there is a constant risk that one of the new strains may spread easily among people. But there is no evidence that any recent strain of avian influenza has been able to spread directly between people.

Avian influenza is an airborne disease. It can also be spread by wild birds and rodents whose movements change in response to flooding.

Higher risk areas (HRAs)

Although the country is free from Highly Pathogenic Avian influenza (HPAI) experience over the winters of 2016 and 2017, coupled with scientific and veterinary opinion indicates that migratory wild waterfowl (e.g. ducks, geese and swans) and gulls represent the most likely pathway for the introduction of HPAI virus (also known as bird flu).

Wild waterfowl and gulls (particularly migratory species) pose a continual threat for the direct and indirect introduction of these viruses into premises where poultry, game birds, pet or other captive birds are kept.

Areas of GB which are at increased risk of the introduction of the HPAI virus into poultry and kept birds from wild waterfowl have been identified, these are referred to as ‘Higher Risk Areas’ (HRAs).  Read more:  disease risk considerations supporting the definition of Avian Influenza Higher Risk Area.

It is important to note that although these areas are at increased risk, poultry, including game birds and poultry kept as pets in all areas of GB remain at risk from wild birds.

Additional measures required in a HRA

The HRAs will primarily be used to target governments’ wild bird and statutory surveillance programmes and to highlight the areas of GB at greatest risk of bird flu being present in wild birds. 

During periods of heightened risk government might consider additional biosecurity through the declaration of an Avian Influenza Prevention Zone (AIPZ).  Such a Zone would be based on risk.

Mandatory housing measures of free range birds will not necessarily be introduced solely in HRAs. Any decision to house birds anywhere in GB would be informed by risk considerations.

If you are planning a new poultry unit you should take into account the risk of HPAI where the unit is planned.

Action for poultry and captive bird keepers

If you keep poultry, including game birds, pet or other captive birds in anywhere in GB you should take steps now to review your biosecurity. This is particularly important if you are in or close to a higher risk area.

We encourage all keepers to follow our biosecurity advice in captive birds it represents good practice - whether you have commercial flocks, smaller flocks, game birds, and pet birds.

There is a legal requirement for all poultry keepers with 50 or more birds to register their premises on the Great Britain Poultry Register. The voluntary registration of premises with fewer than 50 birds is encouraged. 

Higher risk area map

Find out if your premises is in or near a HRA on this Higher Risk Area interactive map.

We only consider that you’re in an HRA if the whole or part of your premises falls within the HRA. All keepers of poultry or captive birds in GB should continue to follow good practice on biosecurity.

Dead wild birds: what to do

Wild birds can carry several diseases that are infectious to people, so it is best that you leave any dead birds alone.

If you find a dead bird of prey, three or more gulls or wildfowl species (particularly wild geese, wild ducks, swans) or find five or more birds of any other species in the same location and at the same time, please report these incidents to Defra’s national helpline telephone (03459 33 55 77 - please select option 7).

Human health implications

Some strains of bird flu can pass to humans but this is very rare. It usually requires very close contact between humans and infected birds. Find out more at: bird flu and human health

How to control the disease

The Notifiable Avian Diseases Control Strategy sets out the disease control measures we would take if Avian Influenza was suspected or confirmed in the UK. 

All birds on the infected premises would be culled. Disease control zones would be declared with movement restrictions and controls on birds, meat, eggs, and anything likely to spread disease within the zones. The outbreak will be controlled in line with the contingency plan for exotic notifiable diseases.


The Avian Influenza and Influenza of Avian Origin in Mammals (Scotland) Order 2006

The Avian Influenza (Slaughter and Vaccination) (Scotland) Regulations 2006

The Avian Influenza (Preventive Measures) (Scotland) Order 2007

The Avian Influenza (H5N1 in Poultry) (Scotland) Order 2007

The Avian Influenza (H5N1 in Wild Birds) (Scotland) Order 2007


Biosecurity means simple procedures or steps you can take to prevent disease. The risk of bird flu in the UK from wild birds never disappears completely so it is essential that bird keepers maintain effective biosecurity all year round. An outbreak of bird flu in a small hobby or backyard flock can have an impact on commercial poultry sector through both the introduction of movement restrictions and temporary loss of exports with other countries.

There are simple actions that can be taken to help reduce the chance of your birds becoming infected. A variety of guidance is available:

Top tips for avian biosecurity

1 page PDF
1.3 MB


Animal Health and Welfare 
Scottish Government
Agriculture and Rural Economy Directorate
Saughton House