Recently, the journals "Nature" and "Science" simultaneously reported the outbreak of avian influenza in Spanish mink farms in October 2022, emphasizing that an H5N1 influenza virus that can be transmitted between mammals may increase the risk of human and wild animals. infection risk. The researchers warn that if careful precautions are not taken, the disease could eventually spread through the population.

In October 2022, mink on a farm in the Galicia region of Spain began to die, and it was initially thought that it might be the impact of the new coronavirus, which had hit some mink farms in other countries. But tests showed that the H5N1 bird flu virus was the culprit. Authorities immediately culled more than 50,000 mink from the farm and quarantined the workers.

Virus samples taken from four mink on the farm, after genetic sequencing, showed some changes compared with the bird flu virus, including a mutation in a polymerase gene T271A. This change helps the H5N1 virus replicate better in mammalian tissues. The change was also found in virus samples from other infected mammals.

Mammals can also be infected with bird flu after preying on birds or swallowing bird droppings, the researchers said. The spread of H5N1 viruses among mammals represents an increased public health risk. Researchers worry that large-scale farming of mink will increase the risk of bird flu outbreaks and even become a breeding ground for various viruses to mutate. Previously, the new crown virus had also spread on a large scale among minks.

Metten Wright, director of the Friedrich Loeffler Institute for Animal Health in Germany, pointed out that the H5N1 avian influenza epidemic has been sporadically observed to spread from poultry to raccoons, foxes, martens, and seals. However, the outbreak that broke out in Spanish mink farms in October 2022 may allow the virus to gain the ability to spread directly among mammals. It means another step in the evolution of viruses to adapt to mammalian hosts.

A recent paper in European Surveillance, published by the European Center for Disease Prevention and Control, also focused on the incident, rekindling longstanding concerns that the H5N1 virus could trigger a human pandemic.