2023-10-18 17:00:00
Updated Wednesday, October 18, 2023 – 17:00
An analysis by researchers at the University of Hong Kong certifies that the new strains of this pathogen have moved continents. They also warn of the threat that this poses
A worker observes the chickens in the Alexandra municipality in Johannesburg, a town that has suffered several outbreaks of avian flu this year.KIM LUDBROOKEFEBrotes The WHO reports new cases of avian flu in mammals: cats in Poland Health They discover a protein that acts as a barrier in the contagion between birds and humans in avian flu
Outbreaks of avian flu are becoming more common. A year ago, the European Center for Disease Prevention and Control (ECDC) confirmed that Europe was suffering the largest epidemic due to this virus, both due to the number of outbreaks in birds and the geographical extension “are unprecedented,” the European organization noted. . The situation has not changed.
According to the latest ECDC bulletin, between June 24 and September 1, 2023, outbreaks of highly pathogenic avian influenza (HPAI), the so-called A(H5,) in domestic birds were reported (25 ) and wild (482) in 21 European countries. They highlight that The current epidemic in wild birds has already surpassed that of the previous epidemiological year in terms of total number of detections of the most pathogenic virus.
Today a study published in Nature certifies these facts. At the same time, it reveals important changes in ecology and evolution of highly pathogenic H5 avian influenza viruses, including a significant change in global distribution. The findings suggest that the epicenter of these viruses has spread beyond Asia to new regions, including parts of Africa and Europe.
The activity of the highly pathogenic avian virus H5N1 has intensified globally since 2021, infecting and killing increasing numbers of wild birds and poultry, as well as posing a risk to mammals (including humans). This is because the feared ‘species jump’ from birds to mammals has occurred, proven through incidental infections in mink and also in gray seals in New England in the USA.
Gustavo del Real, researcher at the National Institute of Agricultural and Food Research and Technology (INIA-CSIC), recalls, as reported by SMC, that “although the H5N1 viruses initially emerged in China in 1996, the appearance of outbreaks with evolved strains of the H5 subtype has not ceased since then, mainly in Asia. This study clarifies the origin and underlying evolution of virus H5N1 highly pathogenic responsible for the bird flu panzootic that emerged in 2021“.
From the University of Hong Kong, Vijaykrishna Dhanasekaran and his team examined the changing origins and trends of H5 outbreaks in highly pathogenic birds using epidemiological data collected by the Food and Agriculture Organization and the World Organization for Animal Health between 2005. and 2022, along with the analysis of more than 10,000 viral genomes complete.
They explain that “using epidemiological, spatial and genomic approacheswe demonstrate changes in the origins of HPAI H5 resurgence and reveal significant changes in the ecology and evolution of the virus.”
During the 2016-17 season, significant outbreaks were identified and genome analysis revealed that the viral lineages originated in Asia, specifically China. On the contrary, two new H5 viruses identified between 2020 and 2022 that emerged from African and European bird populations indicate a notable change in the H5 epicenter far from Asian lands and that moves to other continents.
“Outbreak data show key resurgent events in 2016-2017 and 2020-2021, which contributed to the emergence and panzootic spread of H5N1 in 2021-2022,” they point out. Genomic analysis reveals that “the 2016-2017 epizootics originated in Asia, where HPAI H5 reservoirs are endemic. In 2020-2021, 2.3.4.4b H5N8 viruses emerged in African poultry, with mutations that altered the structure of HA and receptor binding. In 2021-2022, a new H5N1 virus evolved through recombination in wild birds in Europeand experienced a new recombination with low-pathogenic avian influenza in wild and domestic birds during global dissemination,” they explain in the article.
In this way, they determined that these strains had evolved through genetic rearrangement with low pathogenic viral variants as they spread. Therefore, they conclude that “these results highlight a shift in HPAI H5 epicenter beyond Asia and indicate that the increasing persistence of HPAI H5 in wild birds is facilitating geographic and host range expansion, accelerating the rate of dispersion and increasing the potential of rearrangement. As previous H5N1 and H5N8 outbreaks were caused by more stable genomic constellations, these recent changes reflect the adaptation at the interface between domestic birds and wild birds“.
The researchers suggest through their analysis that the increasing persistence of avian flu in wild bird populations is driving the evolution and spread of new strains. “Elimination strategies in domestic birds remain a high priority to limit future epizootics.” Thus They urge greater surveillance of the spread and monitor the prevalence of highly pathogenic avian influenza within global bird populations, as well as the importance of understanding viral evolution to mitigate and react to new strains.
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