The highly pathogenic avian influenza H5 viruses have been found to show major shifts in their ecology and evolution, according to a new study. Between 2020 and 2022, two new H5 viruses were identified to have emerged from African and European bird populations, the study, published in the journal Nature, said. However, the viral lineages originated in Asia, genome analysis has revealed. This indicates that the epicentres of the H5 viruses have shifted from Asia to Africa and Europe.
As low pathogenic viral variants spread among wild birds, they underwent genetic reassortment, and these strains were formed. The tendency of wild bird populations to sustain H5 virus transmission has increased, and the potential for genetic reassortment has also risen.
In 1996, the highly pathogenic avian influenza virus first emerged in poultry in China. The scale of resurgent H5 outbreaks in wild birds has expanded since 2014.
In 2016 and 2017, resurgent events caused by the highly pathogenic avian influenza occurred.
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The activity of the highly pathogenic avian H5N1 virus has intensified worldwide since 2021. This has resulted in the deaths of several wild birds and domestic poultry. Mammals, including humans, have also been at a risk.
The origins of these resurgences, the underlying evolution, and the changing ecology were unclear, but researchers from the University of Hong Kong analysed over 10,000 whole viral genomes, and studied the changing origins and trends of highly pathogenic avian H5 outbreaks using data collected by the Food and Agricultural Organization (FAO) and the World Organisation for Animal Health between 2005 and 2022, and found that the viral lineages originated in Asia, and the epicentres of two new H5 viruses shifted away from Asia to other continents.
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The study found that it is the increasing persistence of avian influenza in wild bird populations that is driving the evolution and spread of new strains. This indicates that there is a need to improve mitigation and elimination strategies to limit future epizootic outbreaks (outbreaks of a disease affecting many animals of the same kind at the same time), the University of Hong Kong said in a statement.
In order to limit viral spread and control the prevalence of the highly pathogenic avian influenza in global bird populations, it is important to implement elimination strategies. It is also necessary to understand viral evolution to mitigate the effects of new strains. There is a need to be prepared against influenza pandemics.
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