Professor Dominic Mellor, Consultant Veterinary Public Health discusses the recent outbreak of avian influenza that has swept across the UK, the importance of monitoring it and the measures in place to protect people.
As part of our role in protecting health, Public Health Scotland supports the management of zoonotic disease outbreaks – diseases that can transfer between humans and animals. One that is currently occurring is avian influenza, commonly known as avian flu or bird flu.
The very widespread outbreak of avian flu across the UK, and much of Europe, through the autumn and winter 2021-22 is the largest seen so far and it is still going on. Avian flu viruses are brought to the UK each year by wild birds migrating south and west for the winter from their summer breeding grounds in the arctic. Migrating water birds, particularly ducks and geese, are usually seen as the main spreaders and seem better able to carry the infection without succumbing to illness or death.
There are many different strains of avian flu virus and, like most other viruses, they are always evolving. Any viruses that are detected are carefully analysed to help understand how the disease spreads and to monitor changes over time.
Avian flu is important because it can cause severe disease and high death rates in captive birds and domestic poultry. This can have a devastating impact on the production of poultry meat and eggs, as well as severe compromise to the welfare of affected birds. In the UK, meat and eggs from poultry are very important sources of nutrition. We consume around 2 million chickens and 35 million eggs [external website] per day. Properly cooked poultry and poultry products such as eggs are safe to eat. It’s always recommended to follow Food Standards Scotland food safety advice [external website] during any outbreak. Furthermore, eggs are also used in the manufacture of some vaccines, such as some of the seasonal flu vaccines. So, our dependency on healthy and thriving poultry production in the UK is perhaps more than many people realise.
Because of this, it’s important to carry out regular surveillance of any dead wild birds reported and closely monitor any outbreaks. Together, these actions help the responsible agencies manage outbreaks effectively as well as increase understanding of the risks of avian flu across industry and the general public.
Keeping birds safe
Scotland’s wild bird populations, both migratory and resident birds, are also essential elements of our iconic natural heritage as well as key components of our ecosystems. As such, they provide intrinsic value for human health. These days, many people keep their own small numbers of backyard chickens, ducks and other birds, and all will be concerned about the health and welfare of their birds when an outbreak of avian flu occurs. General information and advice for small-scale keepers [external website] is available and is important to follow to reduce the risk of transmission to other birds as well as humans.
Humans can be infected with some strains of avian flu viruses, although this is rare, and it almost always follows extended close contact with infected birds. The recent single case [external website] identified in England in December 2021 suggests that human infection with the strains of virus currently circulating in the UK is a possibility.
The UK actively strives to maintain officially disease free status for avian flu to minimise the impact of the disease on poultry production, animal welfare and human health. Animal Health legislation is in place to empower the authorities to investigate suspicion of disease in birds. In confirmed cases, authorities act swiftly to cull and safely dispose of infected birds and impose restrictions to limit spread of virus from infected premises. In this way, disease, and the risk of onward transmission, is eradicated.
An Avian Influenza Prevention Zone [external website] is currently in force across the whole of Great Britain to reduce the risk of the transmission of avian flu to poultry or other captive birds. Despite all of the activity in place to control avian flu, there are ongoing cases throughout the UK in both domestic and wild birds. The risk to the public from the circulating strains of avian flu is very low. However, it is important that people do not touch any sick or dead birds and instead report these to the Defra helpline on 03459 33 55 77.
For more information and live updates on the current situation in the UK and where cases have been confirmed, visit the Defra website [external website].