Multiple independent introductions of highly pathogenic avian influenza H5 viruses during the 2020–2021 epizootic in France
François‐Xavier Briand, Éric Niqueux, Audrey Schmitz, Claire Martenot, Martine Cherbonnel, Pascale Massin, Rachel Busson, Carole Guillemoto, Isabelle Pierre, Katell Louboutin, Florent Souchaud, Chantal Allée, Hélène Quenault, Pierrick Lucas, Anne Van De Wiele, Yannick Blanchard, Nicolas Eterradossi, Axelle Scoizec, Sophie Le Bouquin‐Leneveu, Séverine Rautureau, Yves Lambert, Béatrice Grasland
Abstract
During winter 2020-2021, France and other European countries were severely affected by highly pathogenic avian influenza H5 viruses of the Gs/GD/96 lineage, clade 2.3.4.4b. In total, 519 cases occurred, mainly in domestic waterfowl farms in Southwestern France. Analysis of viral genomic sequences indicated that 3 subtypes of HPAI H5 viruses were detected (H5N1, H5N3, H5N8), but most French viruses belonged to the H5N8 subtype genotype A, as Europe. Phylogenetic analyses of HPAI H5N8 viruses revealed that the French sequences were distributed in 9 genogroups, suggesting 9 independent introductions of H5N8 from wild birds, in addition to the 2 introductions of H5N1 and H5N3.