A team of specialists from St. Jude Children's Hospital (USA) and WHO has documented the rapid evolution of the H5N1 avian influenza virus around the world, as evidenced by frequent calls to vaccinate poultry. The results of the study are published in the journal Nature Communications.

Since the first detection of the avian influenza virus, outbreaks have largely been characterized by seasonal manifestations. However, now scientists note that, most likely, after 2021 “something happened”, after which H5N1 became much more contagious. Since then, outbreaks have occurred every year, infecting new areas and resulting in massive deaths of wild and domestic birds.

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In the new work, the authors infected animals with one of the strains of the pathogen. In the brains of the test subjects, a huge number of viral particles were detected, which leads to much more serious consequences than previous strains. Such rapid variability of the virus suggests that it can acquire new genetic traits, increasing the risk of infection for humans.

Ferrets were also successfully infected in the study. The virus has been found in a growing number of mammals, which could be a worrying sign. So, since the beginning of the year, about nine thousand sea lions, penguins, otters, porpoises and dolphins have died on the northern coast of the United States. It is assumed that the animals died by eating sick birds.

However, at the moment, cases of human infection are rare, and the likelihood of human infection is still low. This is because avian viruses bind to different receptors on the host cell than human viruses. But in order to adapt to infecting humans, a pathogen only needs two or three minor changes in a single protein.

One way to reduce the overall number of bird flu cases and reduce the risk to humans could be to vaccinate poultry around the world, experts say. Some countries, including China and Egypt, have already launched similar campaigns.