Did bird flu ever go away?

The avian influenza virus H5N1 emerged in 1996. It was first identified in Southern China and Hong Kong. Since then, it has spread to Africa, the Middle East and Europe, and most recently it has started appearing in North America.Commercial poultry farmers will be well aware that bird flu is a notifiable disease but everyone should generally be aware that suspected cases in wild birds should also be reported as they are obviously more likely to spread the disease.

In previous years, bird flu has tended to be seasonal, appearing occasionally over the winter period and disappearing in the summer. However, this year, cases have been reported in all seasons. The nationwide Avian Influenza Prevention Zone, declared in the UK on 3 November 2021, was lifted on 16 August 2022. Since then, regional Avian Influenza Prevention Zones(AIPZ) have been declared in Cornwall, Devon, Isles of Scilly and part of Somerset, and also in Norfolk, Suffolk and parts of Essex following a number of detections of avian influenza in poultry and wild birds across the southwest of England. There have also been confirmed cases of bird flu in commercial poultry units in Yorkshire, Essex, Norfolk and Wales.

It is well known that bird flu is usually transmitted by infected migrating wild birds' faeces and because of this, avian flu is a global problem. Having said that, until now North America has largely escaped bird flu, but last year it suffered its second outbreak. Few birds cross the Atlantic, so it’s thought that the virus was spread by birds spending summer in the Arctic, which raises questions about whether the changing climate in the far north is also affecting the spread.

The sharp increase in the number of outbreaks of bird flu makes research into preventing the spread of the disease more urgent than ever, according to Prof Ian Brown, head of virology at the government’s Animal and Plant Health Agency (APHA). The UK has faced its largest ever outbreak of bird flu this year, with over 150 cases confirmed across the country since late October 2021. Pro Brown suggested that this may be partly due to an increasing number of people keeping chickens or ducks in their back gardens. 

Those keeping small numbers of birds do not legally have to register with any authority, although Defra does encourage it so that everyone can be notified in the event of an outbreak. “A good percentage of our cases have been in those types of setting,” Brown said. “They’re in big commercial farms all the way down to somebody keeping two chickens in their back yard. So that is a massive shift in terms of the food security risk, public health risk, animal welfare and poultry exports.”

No-one knows when this outbreak will end, or if it is here to stay, as we don’t yet have a sophisticated enough understanding of the disease. However, given that scientists have identified that the scale and magnitude of bird flu outbreaks seems to be increasing over time, it seems likely that H5N1 is going to be a fact of life for the industry, at least in the short to medium term. In the meantime, scrupulous biosecurity is the most effective method of disease control available, and remains the best course of action for farmers to follow. This and constant vigilance will be required over the coming months to prevent another nationwide outbreak taking hold.