Julia Lechmann, etc.,al. [preprint]The Swiss national program for the surveillance of influenza A viruses in pigs and humans: genetic variability and zoonotic transmissions from 2010-2022. https://doi.org/10.1101/2025.01.28.24319114
Influenza A viruses (IAV) are likely candidates for pandemics. This report summarizes the results of the Swiss national program for surveillance of influenza viruses in pigs and transmissions to humans between 2010 and 2022. Challenges and optimization options in the program are discussed. Nasal swabs or lung tissue samples from pigs with influenza-like signs (e.g. fever, cough) were screened by real-time RT-PCR for swine influenza virus (SIV) genomes, including that of the 2009 pandemic strain A(H1N1)pdm09; positive samples were subtyped for H1, N1, H3 and N2 by RT-PCR and Sanger sequencing. In parallel, humans with influenza-like symptoms and recent contact to diseased pigs were asked to self-sample themselves with a nasal swab. Human swabs were tested for IAV and positive swabs further subtyped to identify potential cross-species transmission between swine and humans. In the pigs, SIV was detected in 375 of 674 farm visits. H1N1 is the only subtype detected in Swiss pigs so far. The (H1N1)pdm09 strain (HA clade 1A) was only detected in seven out of 375 SIV positive farm visits. Phylogenetic analyses from partial hemagglutinin (HA) and neuraminidase (NA) genome sequences indicate that the remaining pigs were infected with the Eurasian avian lineage (HA clade 1C), which is predominant in swine in Europe. The Swiss H1N1 strains form distinct clusters within HA clades 1C.2.1 and 1C.2.2 and seem to evolve comparably slowly. Infection of humans with SIV was identified in five cases. Sequence analysis assigned the five viruses to the Eurasian avian lineage (C), clades 1C.2.1 and 1C.2.2. There was no evidence for sustained human-to-human transmission. Although no critical IAV variants seem to have emerged so far in Switzerland, further surveillance of influenza viruses at the swine-human interface is of major importance.
See Also:
Latest articles in those days:
- Emergence of a genetically distinct cluster of influenza A(H3N2) viruses within subclade J.2.2 associated with hospitalization during the 2024-2025 season in Auvergne-Rh?ne-Alpes, France 6 hours ago
- Interaction between DEAD-box RNA helicase 10 and influenza PB1 polymerase selectively regulates influenza A virus replication 6 hours ago
- Genetic Diversity of Clade 2.3.4.4b H5Nx High Pathogenicity Avian Influenza Viruses Detected in Korea During the 2025-2026 Winter Season and Pathogenicity of H5N1 and H5N9 Viruses 6 hours ago
- Update and optimization of a multiplex RT-qPCR assay to overcome diagnostic failure in emerging influenza A(H3N2) subclades J.2 and K (Peru, 2024-2026) 6 hours ago
- Antigenic and structural analysis of the influenza hemagglutinin lateral patch 6 hours ago
[Go Top] [Close Window]


