The record of 26 H5N1 outbreaks in 2021 has been broken, with 121 cases of the H5 serotype this year, according to Professor Ian Brown, head of virology at the government’s Animal and Plant Service (Apha). That may be due to the growing number of people holding chickens or ducks, Brown said. Many of these owners do not need to register with any authority due to the small number of birds involved. “A good percentage of our cases were in environments like this,” Brown said. “They are on large commercial farms until someone keeps two chickens in their backyard. “So this is a huge change in terms of food security risk, public health risk, animal welfare and poultry exports.” The Apha consortium was set up by the Department for the Environment, Food and Rural Affairs (Defra) at breakneck speed after last year’s outbreaks alarmed poultry farmers and the UK’s first case of bird flu infecting humans. “Over the last 10 years, we have had several cases of bird flu in the UK, but their incidence has been increasing,” Brown said. “Instead of coming every three or four years, we seem to get an event every year and it’s on a larger scale.” The risk to humans remains very low. Since the onset of avian influenza 20 years ago, approximately 600 cases of human-to-human transmission have been reported worldwide. However, the Covid pandemic has highlighted the dangers of other potentially life-threatening diseases – those transmitted to humans by animals. “The more people who come in contact with birds in an uncontrolled way, the greater the theoretical risk of infecting humans,” Brown said, adding that the United Kingdom has “very good surveillance” of viruses. “If we can reduce the burden on birds, it also has a beneficial effect on reducing the risk to humans.” Bird flu is spreading to farmed birds, and researchers are looking at data collected last winter to find out what practices make farms less vulnerable to infection. When the tide began last winter, the government ordered that all birds be kept indoors – known in agriculture as “housing” rather than as a lockdown – meaning that free-range eggs would not be available in Britain for five weeks. Bird flu has recently killed thousands of hooks in the UK. Photo: Danny Lawson / PA The virus is transmitted between birds through close contact: “It is a transmission of droplets – a bit like Covid,” said Brown. Stools and nasal secretions – bird droppings – are other carriers. Infectious feces from wild birds as they fly over farms can be part of the problem. “Even at 4 degrees Celsius, the virus will survive with great joy, infectious, for about eight weeks,” he added. Another area of research is how and why wild birds get sick: the disease is very painful for animals and often deadly. Thousands of birds have died in Scotland, most of them nesting in narrow colonies, as well as seagulls and zucchini. “This is worrying because some of them are endangered and vulnerable to the virus. When these birds come to breed in the summer, they come very close to each other. So it passes snowballs through these colonies. “ The migration of wild birds is probably another factor, and some of the largest are mixed in Central Asian countries such as Kazakhstan, in a version of the Silk Road birds. The virus usually disappears from Europe in the summer, but that did not happen last year. It also arrived in North America only for the second time. Few birds cross the Atlantic, so it is possible that the viruses were transmitted by birds that spend the summer in the Arctic, raising questions about whether the changing climate in the far north is also affecting the spread.
