# Novel Highly Pathogenic Avian Influenza A(H5N1) Virus, Argentina, 2025

**Authors:** Ralph E.T. Vanstreels, Martha I. Nelson, María C. Artuso, Vanina D. Marchione, Luana E. Piccini, Estefania Benedetti, Alvin Crespo-Bellido, Agostina Pierdomenico, Thorsten Wolff, Marcela M. Uhart, Agustina Rimondi

PMC · DOI: 10.3201/eid3112.250783 · Emerging Infectious Diseases · 2025-12-01

## TL;DR

A new strain of bird flu A(H5N1) was found in Argentina in 2025, combining genes from different regions and showing ongoing evolution.

## Contribution

Discovery of a novel triple-reassortant H5N1 virus in Argentina with mixed Eurasian and American lineage gene segments.

## Key findings

- The virus contains gene segments from Eurasian H5N1 and low pathogenicity viruses from South and North America.
- This marks continued evolution and diversification of clade 2.3.4.4b H5N1 in the Americas.

## Abstract

Genomic sequencing of reemerging highly pathogenic avian influenza A(H5N1) virus detected in Argentina in February 2025 revealed novel triple-reassortant viruses containing gene segments from Eurasian H5N1 and low pathogenicity viruses from South and North American lineages. Our findings highlight continued evolution and diversification of clade 2.3.4.4b H5N1 in the Americas.

## Linked entities

- **Diseases:** avian influenza (MONDO:0018695)
- **Species:** Argentina (taxon 260511)

## Full-text entities

- **Species:** H5N1 subtype (serotype) [taxon 102793]

## Full text

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## Figures

3 figures with captions in the complete paper: https://tomesphere.com/paper/PMC12782262/full.md

## References

15 references — full list in the complete paper: https://tomesphere.com/paper/PMC12782262/full.md

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Source: https://tomesphere.com/paper/PMC12782262