#Reassortant High Pathogenicity Avian #Influenza #H5N1 Viruses During the Reemergence in #Uruguay Suggest Increasing #Genetic Diversity in South #America

 

Abstract

Highly pathogenic avian influenza (HPAI) H5N1 viruses of the goose/Guangdong (Gs/GD) lineage have driven a global panzootic since 2020, with clade 2.3.4.4b establishing sustained transmission in wild birds. In South America, early outbreaks were largely associated with the North American-derived B3.2 genotype, which showed limited diversification after its introduction. Here, we report the genomic characterization of eight H5N1 viruses detected in Uruguay during the reemergence of avian influenza in February–March 2026. Complete genomes were obtained from wild birds exhibiting neurological signs, predominantly Coscoroba coscoroba. All viruses belong to clade 2.3.4.4b but exhibit a reassortant genomic constellation distinct from B3.2. The HA, NA, and MP segments retain the Eurasian backbone, whereas internal genes derive from both South American and North American low-pathogenicity avian influenza lineages. PB2 variation distinguishes two closely related viral groups differing in PB2 origin, whereas the remaining genomic segments retain a shared background. Sequence variation in the neuraminidase gene reduced the sensitivity of a widely used N1-specific RT-qPCR assay, highlighting limitations of existing diagnostic tools during viral evolution. These findings confirm the presence of reassortant H5N1 viruses in Uruguay and, together with recent reports from Argentina and Brazil, support an emerging pattern of genomic diversification in southern South America.

Source: 

Link: https://www.mdpi.com/1999-4915/18/5/558

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#Uruguay - #Influenza A #HxNx viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

{Coscoroba Swan. By Charles J. Sharp - Own work, from Sharp Photography, sharpphotography.co.uk, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=179069673}

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On February 19, 2026, park rangers from the National System of Protected Areas (SNAP) reported observing two birds of the same species displaying neurological signs. They were able to access one of the animals, which subsequently died. The carcass was properly preserved and sent to the official laboratory for analysis. The emergency protocol was immediately activated. An area of 5 kilometres around the point of detection was defined. There are no commercial poultry farms within the area under analysis. The Official Veterinary Services of the departments of Maldonado and Rocha are visiting establishments in the area. The survey consists of identifying the establishment and owner; georeferencing; confirming the presence of birds (chickens/multiple species); evaluating management conditions and the existence of bird or other species mortality in the previous week. To date, 40 establishments have been visited and no clinical signs compatible with avian influenza have been observed on any of the inspected properties. Actions continue at the site.

Source: 

Link: https://wahis.woah.org/#/in-review/7281

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