The worst-ever global outbreak of avian influenza

Avian influenza, also known as bird flu, is a viral infection which is evolving, and has recently been directly responsible for the deaths of 15 million domestic birds worldwide since September 2021. A further 193 million birds have been culled. First reported in 1996, the H5N1 strain has jumped from birds to foxes, seals and otters in the UK, with a recent outbreak reported on a Spanish mink farm.

Over the past 50 years, the global population of poultry has increased 6-fold. Many are kept in indoor, cramped and warm environments that provide the perfect breeding grounds for diseases which can be passed onto wildlife.

There is concern that the avian influenza pathogen could be increasingly spread to humans, as mammals are now being infected with avian influenza. These mammalian infections are believed to be caused by animals feeding on dead wild birds infected with the virus.

4 human cases of the bird flu strain H5N1 worldwide have been confirmed since October 2022, 1 occurring in the UK. Most human infections are thought to be of direct and close contact with birds. Human-to-human transmission of the H5N1 strain has never been verified.

Scientists in the Emerging Infectious Diseases journal stated: “If this virus acquires human-to-human transmissibility with its present fatality rate of 50 per cent, the resulting pandemic would be akin to a global tsunami.”

The current death rate of human cases of H5N1 stands at over 50%, killing 456 of the 865 people infected between 2003 and October 2022. Most infections and deaths were in those having regular and close contact with infected birds.

According to the European Centre for Disease Prevention and Control, there is no immediate threat to humans. However, scientists are keeping an eye on further developments and studies are continuing on how the virus is spreading between different species of mammals.