The epicenter of the worst bird flu crisis in history spreads to Europe, leading to the slaughter of 250 million birds | Science

Humanity is facing the worst known bird flu crisis. Data from Vijay Dhanasekaran, an Indian epidemiologist at the University of Hong Kong, shows that since the resurgence of the epidemic in 2020-2021, at least 250 million poultry have been culled globally to nip the epidemic in the bud. The figures are unprecedented: on this occasion, the deaths of more than 100,000 wild birds of 400 different species were also recorded, with a worrying toll among mammals, such as an American mink fur farm in a Galician town observed fatalities. Mass die-off of sea lions on the beaches of Caral and Peru. New subtypes of avian influenza viruses are everywhere. Dhanasekaran’s team investigated the evolution of the pathogen and warned on Wednesday that the “epicenter” of the crisis had shifted from Asia to Europe and Africa. Experts are holding their breath as a typical November outbreak is imminent due to the arrival of migratory birds from the Arctic.

The current lineage was detected in geese in Guangzhou Province, China, in 1996. There are two characteristic proteins on the surface of avian influenza viruses: hemagglutinin (H) and neuraminidase (N). There are 18 types of H and 11 types of N, with many possible combinations. Guangdong goose virus is an H5N1 virus that can spread rapidly among poultry and cause hemorrhagic diseases with a mortality rate of more than 40%.

Two different influenza subtypes can arise simultaneously in the same cells in an animal, causing a phenomenon called genetic recombination to create a third subtype that is a mix of previous subtypes. Dhanasekaran’s team discovered key events in the evolution of viruses. In 2016, an H5N8 virus that was particularly virulent to ducks originated in China. In 2020, the H5N8 subtype classified as emerged in African poultry. According to Dhanasekaran’s research published in the journal, the H5N1 subtype emerged in 2021 through genetic recombination in European wild birds and has caused “unprecedented outbreaks in wildlife on five continents since November of that year” break out” nature.

Indian epidemiologists warn: “The epicenter of these highly pathogenic viruses has shifted to new areas, increasing their chances of infecting a wider range of animals, including mammals.” Avian influenza viruses have been reported in seals, foxes, raccoons, American Species such as lions, lynx and bears are found. It has also spread to humans erratically, such as when a 9-year-old girl nearly died in late 2022 after living with sick chickens in a village in Ecuador. “They increase the chances of the virus adapting, thereby increasing the likelihood of a pandemic,” Dhanasekaran warned.

The team analyzed the genomes of 10,000 viruses and examined outbreaks documented by the World Organization for Animal Health and the United Nations since 2005. The authors emphasize that the prevalence of the virus in wild birds accelerates the spread of the pathogen and exponentially increases the risk of genetic recombination. “The threat of viruses spreading to humans is ever-present. This is largely due to the virus’s ability to evolve rapidly. It can acquire mutations that help it stick better to receptors on human cells, or it can acquire transmission through aerosols capabilities,” Dhanasekaran explained. The Indian scientist said: “The most worrying thing is the genetic reassortment of H5 viruses (from birds) with human influenza viruses, which has occurred in previous pandemics, such as the 1957 and 1968 pandemics .”

Peruvian ornithologist Victor Gamarra warned that the current animal pandemic – what amounts to an animal pandemic – has affected “hundreds of thousands of wild birds” around the world. On November 13, 2022, Peru detected its first case of H5N1 in a pelican. The epidemic spread rapidly along the coast, and by mid-March, at least 100,000 wild birds had been found dead, belonging to 24 species, some of which were threatened, as Gamarra’s team detailed in a recent study. This pathogen killed 20% of the pelicans in a Peruvian marine reserve. The ornithologist stressed that the total number would be much higher because his estimate did not include what happened outside protected areas, where the death toll could reach 500,000.

“The virus has spread throughout South America. They are no longer just birds, there are thousands of dead sea lions from the Pacific coast to the Atlantic.” Gama, a researcher at the Natural History Museum of the National University of San Agustin in Arequipa La sighed. “As birds are about to start a new migration, the situation may become more delicate. There may be recombination of the virus and maybe we will talk about a second wave in South America,” he warned. “This virus spreads quite quickly, so studies like Dhanasekaran’s may be out of date. That’s the huge threat of this virus: We’re not prepared to deal with the speed of it.”

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