Epidemiological insights into Porcine Influenza Disease in Guinea, West Africa, 2017-2019

National audience Besides the seasonal flu (H1N1, H3N2...), the 2009 A(H1N1)pdm09 pandemic highlighted the critical role of pigs as “mixing vessels” for Influenza A viruses (IAV), allowing viruses to reassort and potentially infect humans. In West Africa, Guinea rears substantial swine populations with limited data about the Influenza A viruses circulation in pigs. Methods: Between 2017 and 2019, we conducted a cross-sectional study in six of eight administrative regions of Guinea. 769 pig sera collected from 25 farms were tested for Influenza A-specific IgG antibodies using two commercial ELISA kits. A selected sub-sampling was further tested by immunohemagglutination assay (IHA) for A(H1N1)pdm09 (strain A/swine/France/57140136/2014) and A(H3N2) (strain A/ Victoria/361/2011 (human)). Results: More than half of the farms had influenza seropositive pigs with an overall seroprevalence of 25.0% (192/769) and substantial regional heterogeneity. The central part of the country i.e. Mamou (75.0%), Kindia (40.2%), and Faranah (26.7%), as well as the capital Conakry (28.6%), showed higher prevalence, while the forest Nzérékoré (7.5%) and the North coast Boké (7.7%) had markedly lower rates despite their hosting intensive pig raising. IHA confirmed widespread circulation of A(H1N1)pdm09 across all regions, whereas A(H3N2) was detected only in Kindia and Nzérékoré. In multivariable analysis, older age group and region of origin were independently associated with seropositivity: pigs aged 6-11 months (aOR = 12.1) and ≥ 12 months (aOR ~ 15.0) were significantly more seroprevalent compared with those aged 2-5 months. Pigs from Mamou had markedly increased odds (aOR = 13.8), whereas those from Boké and Nzérékoré were significantly lower (aOR ~ 0.11). The final model showed excellent discrimination (AUC = 0.83). Conclusion: The A(H1N1)pdm09 IAV is still actively circulating in pig farms in Guinea with strong age- and region-specific patterns. These findings provide baseline evidence to support integrated One Health surveillance and targeted influenza prevention strategies at the human-animal interface.