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Volume 31, Number 6—June 2025

Dispatch

Highly Pathogenic Avian Influenza A(H5N1) in Wild Birds and a Human, British Columbia, Canada, 2024

Chelsea G. HimsworthComments to Author , Jessica M. Caleta, Agatha N. Jassem, Kevin C. Yang, James E.A. Zlosnik, John R. Tyson, Laurie Wilson, Kevin S. Kuchinski, Jolene Giacinti, Megan Willie, Tony D. Redford, Maeve Winchester, Caeley Thacker, Yohannes Berhane, Theresa Burns, Natalie Prystajecky, and Shannon L. Russell
Author affiliation: British Columbia Ministry of Agriculture and Food, Abbotsford, British Columbia, Canada (C.G. Himsworth, T.D. Redford, T. Burns); British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada (J.M. Caleta, A.N. Jassem, K.C. Yang, J.E.A. Zlosnik, J.R. Tyson, K.S. Kuchinski, N. Prystajecky, S.L. Russell); Canadian Wildlife Service–Environment and Climate Change Canada, Delta, British Columbia, Canada (L. Wilson, M. Willie); Environment and Climate Change Canada, Ottawa, Ontario, Canada (J. Giacinti); British Columbia Ministry of Water, Land and Resource Stewardship, Nanaimo, British Columbia, Canada (M. Winchester, C. Thacker); Canadian Food Inspection Agency, Winnipeg, Manitoba, Canada (Y. Berhane)

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Figure 3

Phylogenetic relationships and possible origins of the neuraminidase (NA) segment (Am4N1) of the clade 2.3.4.4b D1.1 genotype detected in fall 2024 as part of a study of highly pathogenic avian influenza A(H5N1) in wild birds and a human, British Columbia, Canada, 2024. The maximum clade credibility tree was inferred by using BEAST v2.7.7 (6), incorporating NA gene sequences from D1.1 viruses and closely related sequences from wild birds detected in British Columbia and National Center for Biotechnology Information databases. Analysis used an uncorrelated relaxed log-normal clock, the Hasegawa-Kishino-Yano substitution model without gamma rate heterogeneity, and a coalescent Bayesian skyline tree prior. The posterior distribution was approximated using 100 million Markov chain Monte Carlo steps, sampled every 10,000 steps, with a 10% burn-in. All NA segments were identified as Am4N1 by GenoFLU except those indicated with a black dot on the tree tip label (⦿); non-Am4N1 sequences were classified as unassigned. Shaded box indicates NA segments from D1.1 and D1.2 H5N1 viruses. D1.2 samples are bolded and italicized. Node support values and branch lengths indicate the evolutionary divergence and probable reassortment timeframes leading to the emergence of the Am4N1 NA segment in the D1.1 genotype.

Figure 3. Phylogenetic relationships and possible origins of the neuraminidase (NA) segment (Am4N1) of the clade 2.3.4.4b D1.1 genotype detected in fall 2024 as part of a study of highly pathogenic avian influenza A(H5N1) in wild birds and a human, British Columbia, Canada, 2024. The maximum clade credibility tree was inferred by using BEAST v2.7.7 (6), incorporating NA gene sequences from D1.1 viruses and closely related sequences from wild birds detected in British Columbia and National Center for Biotechnology Information databases. Analysis used an uncorrelated relaxed log-normal clock, the Hasegawa-Kishino-Yano substitution model without gamma rate heterogeneity, and a coalescent Bayesian skyline tree prior. The posterior distribution was approximated using 100 million Markov chain Monte Carlo steps, sampled every 10,000 steps, with a 10% burn-in. All NA segments were identified as Am4N1 by GenoFLU except those indicated with a black dot on the tree tip label (⦿); non-Am4N1 sequences were classified as unassigned. Shaded box indicates NA segments from D1.1 and D1.2 H5N1 viruses. D1.2 samples are bolded and italicized. Node support values and branch lengths indicate the evolutionary divergence and probable reassortment timeframes leading to the emergence of the Am4N1 NA segment in the D1.1 genotype.

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